EXCLUSIVELY FOR THE TRANSMITTINGVOLUME VI SHORT WAVE MAGAZINE 219 CELESTION Here are two excellent Celestion Speakers with dimensions which make them ideal for use in small domestic

EXCLUSIVELY FOR THE RADIO EXPERIMENTER & TRANSMITTING AMATEUR

VOL. VI No. 4 JUNE 1948

iï SHORT WAVE MAGAZINE JUNE 1948

*EX -SERVICE MATERIAL We are not "SURPLUS" dealers, and we are not normally very enthusiastic about surplus Service Equipment, but the Crystal Calibrated Wavemeter detailed below, and the panel mounting meters constitute something of special interest.

WEBB'S TYPE " D2 " CALIBRATED WAVEMETER

A most useful piece of ex -Government equipment, essentially a Crystal calibrator giving markers at every 100 Kc/s, and also discriminating markers at 1,000 Kc/s, combined with continuous calibration on dial reading single kilocycles between each 100 Kc/s. It is applicable to both Receiver calibration or Transmitter monitoring, and for the latter purpose a telephone jack is incorporated. It is exceptionally well made, with refinements such as temperature -compensating Condensers and separate 100 Kc/s and 1,000 Kc/s Crystals, which feature gives a greater accuracy and reliability than the dual type Crystal. Incidentally, the Crystals alone would cost more than our prices. Contained in neat metal case with hinged top lid, overall size 7e" x 7e" x 6e" high, and with stout outer wooden case for heavy transport use. Each instrument has been tested and adapted by Webb's for either operation on 62v A.C. or 6 volts D.C. The Wavemeter comes to you ready for immediate operation from 6.2 volts A.C., with easy internal provision for change-

over to 6 volts D.C. The original Army Service Manual of 26 pages, with full circuit diagrams, is included, also a page of Webb's " Simplified Instructions." PRICE £6 17s. 6d.

Webb's " D2T " Transformer for external connection from 210, 230, 250 volts A.C. ... ... ... ... 14/ -

PANEL -MOUNTING METERS We believe we have the " cream " of the ex -Government single range Meters, and at our prices every experimenter should invest in a few-even if you have no immediate use for them, you will never again have the same opportunity at anything like these figures. Each Meter is new and cartoned in maker's boxes.

Flush -mounting External' Flange 21" square. Fixinghole, round, 2*"diameter: 0/5 milliamps ... 5/9 each 0/'5 amp. R.F. with self-contained thermo-couple ... ... ... 5/9 each The internal thermo-couple can be disconnected, when the fundamental movement is a sensitive milliammeter, full-scale deflection between 1.5 and 3 m/A.

Four of the above meters (two of 0/5 m/A and two of 00 amp. R.F.) at special rates. Four for 21/- (Post free 22/-). 0/150 milliamps ... 6/6 each 0/1 milliamp ... 10/- each

Flush -mounting 21" round type meters External Flange 31" dia. -

Fixing hole, 21" diameter : 0/1 amp. R.F. with self-contained thermo-couple ... ... ... 7/6 each 0/20 volts A.C. (moving iron) 8/6 each 0/15 volts A.C. (moving iron) 8/6 each POST CUSTOMERS.-Please add 1/- extra on orders (except special 22/- offer of four specified

meters).

`Yeibbs 1hdh.o ie 11, SOf/O ST., vxfORD sr., zo r-

Telephsne: Gerrard 2089 Shop hours : 9 a.m.-S.30 p.m. Sau., 9 a.m -I p.m.

VOLUME VI SHORT WAVE MAGAZINE 217

"AY O" ELECTRONIC

TEST METER

D.C. Volts : 2.5mV. to 10,000v.-Maximum input Resistance

IIII MD.

D.C. Current : 0.25 µA to I amp. -150 mV. drop on all ranges.

A.C. Volts : 0Iv. to 2,500v. R.M.S. up to 1.5 Mc/s. With external diode probe 0Iv. to 250v. and up to 200 Mc/s.

A.C. Output Power : 5mW. to 5 watts in 6 different load resistances from 5 to 5,000 ohms.

Decibels : -10db. to +20db. Zero level 50mW.

Capacitance : 0001 µF to 50µF.

Resistance : 0.2 ohms to IO Mn.

Insulation : 0 1 Mn to 1,000 M.D.

Sole Proprietors and Manufacturers:

This figure represents the ratio of measurement that can be

made on the principal ranges of this versatile instrument. These

measurements can be made

with the simplicity of an ordinary multi -range test meter.

In addition, the "Avo " Elec-

tronic Testmeter offers you the facilities of a laboratory valve

voltmeter for use on frequencies

from D.C. up to 200 Mc/s.

Fully descriptive

leaflet available on application

^'rza'ñ:áäx;.r

§c4-26teeGi'r¡ Zw2zezz7íS

THE AUTOMATIC -.COIL WINDER & ELECTR'ICAI: EQfn>. et)''.;,.J.1D.'.

W I:+N D ER H.O U.S E .- DO U G L'A f STD E l «LON6 O N 5 W-?;-1'ELEPHGNE.:VICTORIA3ca4/9

A

218 SHORT WAVE MAGAZINE TUNE 1948

THEHAM BAN DER RECEMVERICATIONS

" The Hottest Performance

ever at this low price."

That's the verdict of amateurs

who have already tried this

wonderful receiver.

* PRICE £22:10:0. Plus 10s, carriage and packing charge

It covers all Ham Bands. From 160-10 metres including the new 21 me bands

THAT'S WHY IT'S THE BEST SELLER ON THE MARKET AT THE PRESENT TIME

Don't Delay. Write now for Illustrated Brochure. H.F. Facilities

RADIOVISION (Leicester) LTD., 58/60 Rutland St., Leicester. 'Phone: 20167

A NEW AND IMPORTANT SYMBOL

introducing "MICRO -METRIC" COILS

Coils for the modern communications,

or DX receiver cannot be large because space is at a premium. " MM " Coils are designed to occupy a minimum of space without sacrifice of performance. Many designers have specified " MM" Coils for high-class receivers ... now, a complete range is available to the home constructor.

Send Stamp for interesting Bulletin "S" which gives full details

LONDON TELEVISION COMPANY LTD 694 LEA BRIDGE ROAD, LONDON, E.I0. Phone: Leytonstone 4380


CELESTION Here are two excellent Celestion Speakers with dimensions which make them ideal for use in small domestic receivers, as extension speakers, for car radios, intercommunication sets, and, Model P2V can also be used as a microphone.

The Midget 2 Cabinet Model CTII7 (as illustrated) uses the P2V Speaker in its bakelite cabinet of modern design which is available in a variety of pleasing colours.

Chassis Model P3CO. Dia 3f". Baffle opening 3". Voice coil impedance at 400 cps., 3 ohms. Pole dia e". Flux density gauss 7,700. Total gap flux 24,000. Peak power capacity I watt.

Price less transformer (Suitable for outputs 1-5 ohms)

WHERE TO BUY CELESTION SPEAKERS The Public are requested to order from their local Radio Dealer.

Wholesalers are supplied by the Sole Distributors : CYRIL FRENCH LTD., High Street, Hampton Wick, Middx. Phone: KlNgston 2240.

£1:9:6

MIDGET 2 CABINET MODEL CTII1 Size : Height 4;" Width 61" Depth 2;"

PRICE, complete in cabinet £2: 3:6 TECHNICAL DETAILS OF CHASSIS MODEL P2V. Dia 2é" Baffle opening 2;". Voice coil impedance at 400 cps., 3 ohms. Pole dia -7". Flux density gauss 8,500. Total gap flux 8,000. Peak power capacity á watt.

Price less transformer £ I.7. O (Suitable for outputs 1-5 ohms.) Write for Brochure "S.W." It gives details of all Celestion Chassis and Cabinet Speakers.

Manufacturers should please communicate direct with:

CELESTION LTD., KINGSTON -ON -THAMES, SURREY Phone: KlNgston 5656, 7, 8 and 9

ODEON RADIO 6,eztythi9 ¡oz the ,iniateuz

G4HV SUPPLIERS TO RADIO SOCIETY OF GREAT BRITAIN, HOME OFFICE, ADMIRALTY, ETC

VFO UNITS VFO exciter section from T43 transmitter. Frequency coverage 2.0 to 12.0 Mc/s, ganged tuning. Valve line-up 807 oscillator. 807 doubler, three 807's parallel driver. Dial calibrated in Mc/s, with vernier drive. Fits standard rack. External power supply of 500v required. 807 keying valve included. These units are brand new and a very fine job. Circuit diagram supplied. Price without valves E10, or complete with six 807's E15.

TRANSMITTING VARIABLE CONDENSERS Cyldon 30+30 27/6, 60+60 30/-, 100+100 37/6, Spacing 08". Labgear 50+50 spacing 1" 37/6. Eddystone 60+60 spacing 068", 54/6. Raymart new range of Tx tuning condensers, of excellent design and superior finish :-

50pf 45/-, I00pf 55/-, 50+50 55/-, 100+100 65/-. All the above have I5" plate spacing and will withstand any voltages likely to be encountered in amateur use.

LOW -LOSS FEEDER CABLE Telcon K25 Transmission Line, consisting of twin conductors moulded into a flexible Telco- thene ribbon approximately é" wide. Impedance 300 ohms, attenuation at 30 Mc/s. 0.6 Db. per 100 ft. Ideal for matching into a folded doublet or "T" beam. 9d. per yard. Telcon K24 Transmission Line-similar to the above, but with closer spaced conductors producing an impedance of 150 ohms in a feeder approximately é" wide. 9d. per yard.

NEW VALVES at LOW PRICES 3-T, E2 ; 5U4G, 10/6 ; GU50, 17/6 ; 807, 15/- ; TZ40, 35/- ; RK20A, 35/- ; 6L6G, 10/-; 830B, 20/- ; 866, 27/6 ; 6AK5, 12/6 ; 9001, 9002, 956, 8/6 ; 114, 6AC7, 10/- ; EF50, 7/6 ; 6K7, 7/6.

Appointed distributors of EDDYSTONE, RAYMART, DENCO, and LABGEAR products

ODEON RADIO 56 COLLEGE ROAD, HARROW, MIDDX.

Telephone : HARrow 5778

220 SHORT WAVE MAGAZINE JUNE 1948

Lyons Radio 3 GOLDHAWK ROAD, SHEPHERDS BUSH, LONDON, W.I2

Telephone: Shepherds Bush 1729

We have over 25 different types of Cathode Ray Tube Indicator units in stock. The following two are typical of the outstanding value we offer :

Indicator Unit Type I84A Fitted with 2 C.R. Tubes (I-VCR517/A, 5" screen and 1-VCR139, 2;" screen), 17 valves (including 5-EF50's). Numerous components including metal rectifiers, resistances, condensers, etc. Good condition. Price E3/17/6 (carriage 7/6).

Indicator Unit Type 62A Fitted with VCR97 (an excellent television or oscilloscope tube) and 21 valves (including 12

EF50's). Other components include Muirhead slow motion drive,2 additional slow motion drives with variable condensers, big selection of switches, condensers, resistances, transformers, etc. Practi- cally new. Price £4/5/- (carriage 7/6).

The second edition of our 1948 illustrated catalogue will be shortly available. If you are not already on our mailing list, be sure to send for your copy. (Please enclose 3d. stamp with request)

R.F. Units Type 26

The article on page 160 of Short Wave Magazine for May quotes these as being not commonly available but we now have a limited number to offer. In good condition and including valves. Price 27/6 (postage 1/9). Also type 27 at the same price.

R.F. Units Type 25

Brand new in maker's sealed carton. Valves included. Price 16/6 (postage 1/9). Also type 24 in good used condition and including valves. Price 12/6 (postage 1/9).

Valves Specials for this month-All brand new American metal. OZ4, 7/6; 12817, 5/9; 12SC7, 5/3; (postage 9d. each).

Mains Transformers Primary tapped from IOOv to 250v in IOv steps. Secondaries : 500-0-500v at 250mA, 300v at I OOm A, 12v at I amp, 6.5v at 3.5am p, 4v at 3.5am p. All connections go to engraved terminal boards. New and unused. Price 47/6 (carriage 3/6).

STATION R.I155 magnetrons, etc, STATION R.1155. The R.A.F. receiver R.1155 is still one of the best communication receivers obtainable to -day, in fact it is fitted to most of our modern aircraft. You may have been tempted to purchase one of these, but have hesitated on account of the fact that modifications are required, and because you have to make your own Power Pack, output stage and loudspeaker. You can now obtain Station R.1155 which is all ready to play just as soon as you connect to the AC mains. Our technicians have modified the receiver and our factory has produced the power unit and output stage, together with the loudspeaker as one unit fitted in a first-class cabinet, designed to stand on the top of the receiver. The two go very well together and make Station R.1155 an installation you will be proud to own. Price 618-10-0, plus 12/6 carriage, plus 10/ -for transit case.

MAGNETRONS. U.S. made. Mounted in unit, complete with magnet-spark gap and other electrical and mechanical detalle. Price 212/10 -plus £1 for carriage and packing case.

TELEVISION UNITS. The modern trend of television construction i s to build the set as separate units. Now one of the most tricky units to build is the wide band amplifier essential for good picture reception. We are able to offer, for less than the value of the valves alone, an ideal 8 -valve unit which has a response curve virtually fiat from 12-18 Me/s. By fitting an oscillator valve, quite.a simple job (we will give details where requested) the unit can become the perfect picture receiver. Signals with a field strength as low as 20 micro- volts can be received quite well. The unit is fitted with a detector and amplifier valve, and this can act as video amplifier or A.F. Amplifier. We are pleased to be able to offer these units complete with valves and in perfect order at 55/- each, plus 2/6 postage and packing. If you Intend building a T.V. receiver, we suggest that you order by return.

RADIO UNIT `Q.' Here is your opportunity to purchase for 12/6 equipment which must have cost at least £25. This is not quite a complete receiver, so we call it RADIO Unit 'Q'. It contains amongst other things a strong chassis, 18 in. X 6 in. X 35 in., fitted with 13 Amphenol type Valve Holders. Among the parts mounted on the chassis are relays, 1 mfd and 2 mfd can type condensers. Ceramic variable condensers, small transformers and chokes, grid caps and Pye plugs, etc. Three banks of Mica condensers (approximately 36). Also eight Paxolin panels, 6 in. k 21 in., with feet containing approximately 60 assorted resistors and 25 assorted tubular condensers. The special bargain price of this unit is only 12/6 Pins 3/6 carriage. The supply is limited, so time is precious, don't delay, order immediately.

AC -348. We have converted a number of BC.348 (£100 class communications receivers). Fitting on A.C. power pack in place of the dynamotor and carrying out necessary wiring alterations. The price of these " ready to work " receivers is £22/10/- plus 17/6 f or wooden packing case, insurance and, carriage.

RECEIVER/TRANSMITTER No. 18. Thais a combined Receiver/Transmitter of the Walkie-Talkie type. Frequency coverage 6-9 hie/s complete with six valves, and in case which is fitted up for batteries (not included). PRICE £4/10/-, carriage 10/- extra. DATA BOOBS. Copies from official publications, giving circuit diagrams, component values and useful notes: BC.342 - BC.348 - B0.312 - B0.221 - R.26S - R.103a - R.107 - M.C.R1 - R.1155 - W/5.22 - RT.18 - W/S19 - R.1116A-all at 2/3 each, also Walkie-Talkie 58, 3/8. " Demobbed " valves, 2/8. LIST free on application with stamp. 206 BARGAINS described.

Il you wish you may pay by instal- ments, but you must send a deposit of at least 25% with your order.

W. D. SALES, 4 Electron House Windmill Hill, Ruislip Manor, Middx.


AgerN14....

<LODEN 144>IER CO. LTD

DE LUXE AND POTTED TYPE TRANSFORMERS

MAINS TRANSFORMERS

D.T.M.11. 250-0-250 60 m/a

D.T.M.12. 275-0-275 120 m/a

D.T.M.13. 350-0-350 120 m/a

D.T.M.14. 425-0-425 150 m/a

D.T.M.15. 500-0-500 150 m/a

D.T.M.16. 650-0-650 200 m/a

D.T.M.17. 750-0-750 250 m/a

Also available in larger sizes

MAINS TRANSFORMERS

P.T.M.I I. 250-0-250 60 rn/a

P.T.M.12. 270-0-275 120 m/a

P.T.M.I3. 350-0-350 120 m/a

P.T.M.I4. 425-0-425 150 m/a

P.T.M.I5. 500-0-500 150 m/a

All above available in 4 v or 6 v filament windings. P.T.M.16. 650-0-650

200 rn/a

We welcome your enquiries for all types of Transformers

WODEN TRANSFORMER CO. LTD.

MOXLEY ROAD, BILSTON STAFFORDSHIRE

TELEPHONE : BILSTON 41959/0

For every need of consistently accurate electrical measurement, there is a Pullin Instrument.

Miniature ® Industrial Portable O Laboratory Pattern O Single or Multi -range

Send your instrumentation problems to us.

MEASURING INSTRUMENTS (PULLIN) LTD Address all enquiries to Dept. T Electrin Works, Winchester Street, Acton,W.3. Telephone: Acorn 4651/4

J.T.L.


AMERICAN FREQUENCY METERS BC.22I. A further purchase of this superb instrument. Frequency coverage 125-20,000 kcswith accuracy of.01 per cent, on all ranges. Incorporates crystal -controlled oscillator, heterodyne oscillator and audio frequency amplifier. Complete with plug-in Xtal, THREE sets of valves, calibration charts, and Instruction Manuals. Operates from internal batteries, but ample space in battery compartment for mains pack. BRAND NEW IN MANUFACTURER'S CASES AS SHIPPED FROM U.S.A. Well worth over f50, but a real " buy " for the discriminating purchaser at ONLY f25. (Carriage I0/-.) R.A.F. R.F. UNITS (SHORT WAVE CONVERTERS). A complete ready-made short wave converter that -requires little adaption. Normal voltages input. TYPES 24 and 25 cover 15-30 mcs & 30-45 mcs, respectively, and incorporate a five -point switch for fixed frequency operation. This is easily replaceable with a 15 pf 3 ganging type condenser to make a tuneable unit. Complete with 3 valves. Slightly used models at 16/6d. each, or BRAND NEW IN MAKER'S CARTONS, 25/- ea. (Postage I /6). TYPES 26 and 27 are tuneable converters covering 45-60 mcs and 60-80 mcs respectively. A 3 in. slow motion dial is fitted Complete with 3 valves. Slightly used models at 27/6d. each, or

`BRAND NEW IN MAKER'S CARTONS, 50/- ea. (postage, 1/6).

INDICATOR UNITS TYPE 6. Containing 6+ in. tube VCR 97, E.F 50s, EB 34s, etc., etc. Readily con- vertible into an oscilloscope (vide Wireless World, May, 48). ONLY 67/6 (carriage, etc., 15/-). We can also supply the complete set of two transformers and three chokes specified for the above conversion at E6. (Carriage, 5/-).

R109 SHORT WAVE RECEIVER. The ex -Army 8 -valve superhet covering 1.8-8.5 mcs in two switchable bands. Has built-in 3 in. P.M. speaker. Circuit employs B.F.O. Operates from 6v DC through vibrator unit which can be removed to make a normal battery receiver. Complete in every way with vibrators, valves, etc., and instruction book. Size 14 in. x 10 in. x 11 in. ONLY f6/I5/-. (Carriage, etc., l0/-.)

C.W.O. PLEASE. S.A.E. FOR LISTS.

U.E.I. CORP The Radio, Corner, 138 Gray's Inn Road, London, W.C.I ('Phone : Terminus 7937) '

Open until I. p.m. Saturdays ; we are 2 mins. from High Holborn, 5 mins. from King's Cross

4 -VALVE SUPERHET... HERE IS A SUPERHET which will bring you dozens of short-wave stations just as soon as batteries and phones are connected. 6 to 9 mc/s-four 2 -volt valves-slow-motion drive-size only 6' x 5" x 92"-complete as illustrated

Postage and insurance 2/6

fitted with plug-in jack. Post free 9 Correctly matched headphones, /- Suitable H.T. battery, 9/-

W H E A T S T O N E BRIDGE (new). Fitted in beautiful teak case ;

using heavy stud type selector switches and a precision galvanometer. Plus packing & insurance, 2/6 E2/ 5-

MAINS TRANS. Drop - through type. Primary 200-250 volts, Secondary 350-0-350 80 mA, 5 volts 2 amps, 6.3 volts, £ 1

3 amps. Post paid

EX -RAF AMPLIFIER 1134. Ideal for use with a microphone, or can be used as an amplifier without modification. Complete with wooden Post transit case. free I7

29'6 BC348, as new. 28 f volt. Plus 10/- packing Fitted internal AC Power Pack. 200-250 volts. Plus f22 IO/- packing 24," FLUSH MOUNTING MILLIAMMETER. Moving coil, Bakelite case, 0-I FSD. 36 Brand new. Post free 2+" FLUSH MOVING COIL AMMETER 0-25. Post free 12 ASSORTED MAGNETIC RELAYS for experimental 12/9 purposes. Post free

PHOTO -ELECTRIC - CELL.

Dozens of applications, e.g., burglar alarms, counting, door-

14/6 opening, etc. 28 VOLT MOTORS (new). 7/6 As used on BC453. Post free

NUTS, BOLTS, WASHERS, small sizes for model making. Three gross assorted 7/6

MULTIMETER, 17 ranges. AC/ DC volts, m/amps and ohms. New and perfect fT TELESCOPIC AERIALS. Col- lapsed 15", extended 8' 3". Terri- fically strong and flexible.

Post free

EX-R.A.F. CARBON PILE VOLTAGE REGULATOR.

Post free §/ 6 TELEVISION CONSTRUC- TION MANUAL (by 3/6 Bernards). 3d. postage

SCREENED FLEX. PVC covered. 100 yards 1®/'

Write to Dept. "M"

INSTRUMENT CO. 244 HARROW ROAD, LONDON, W.2. Cun. 0508


ALEC DAVIS SUPPLIES LTD. Tel.: MUSeum 4539 18, TOTTENHAM COURT

We are now able to offer a w valves, all of which have been ful

D.1. Mazda. Television Diode. Glass seal construction. 4v- 0 2a, 00v. R.M.S. anode volts. Used as diode probe, etc. 3/6

EA50. Mollard. Television Diode. Glass seal construction. 6.3v -15a, 50v R.M.S. anode volts. Used as diode probe, etc. 4/-

EB34. Mollard. Double -Diode. Separate cathodes. Octal base. 6.3v 2a, 50v R.M.S. Anode volts. Used as noise limiter,

etc. 1 .

EBC33. Mallard. Double -Diode -Triode. Octal base. 6.3v -20. Amp Factor 30. Top Cap Grid. Slope 3.6ma/v. Used as superhet second detector. 4/6

EF38. Mollard. " Straight " R.F. Pentode. Octal base. 6.3v 2a. Top cap grid. Slope 1.8ma/v. Used as High Gain LF amplifier, etc. 5/8

EF39. Nullard. " Vari -Mu " R.F. Pentode. Octal base. 6.3v. .2a. Top cap grid. Slope 2.2ma/v. Used RF or IF stage, etc. 5/6

EF50. Mollard. Television High elope Pentode. Pressed glass B9G base. 6.3v .3a. Slope 65ma/v. VA 300v Vsg 250v. Television and short wave RF, IF and VF stages. Max. Frequency 100mc/s. 6/-

P.81, Mazda. Special oscillator or high gain triode. Mazda octal base. 6.3v .6a. VA 250v. Slope 7ma/v. Used as high gain LF stage. Television or HF oscillator. Max. Frequency 100mc/s. 3/.

PM258. Mollard. 6v '25a. Directly Heated triode. VA 250v. Slope 3.25ma/v. Watts output 2. 4.pin British base. 3/-

P11240. Mollard 4v. 1 8a. Directly heated output pentode. 5 -pin British. VA 500v. VeG 300v. Watts output 5.0. (Can be supplied In matched pairs) 5/6

SP41. Mazda. Television RF pentode. 4v lamp. Mazda octal base. Top grid. VA = Vsg = 250v. Slope 8ma/v. Used as LF, RF, IF, VF, amplifiers max. frequ. 100mc/s. 3/-

SF81. Mazda. As SP41 bot 63v '6a heater. 3/- 5130, Cossor and G.E.C. Gas stabilizer. 4 -pin British base.

Striking volts 180 approx. Burning volts 120 approx. Max. current range 70ma. 3/8

ROAD, LONDON, W.I. Tel.: MUSeum 2453 ide range of Eæ -Govt, surplus ly tested on our own premises

5040. Large full wave rectifier 5v. 3a, 500v 51.30.8. 225ma D.C. Octal base. 8/8

6R6 Metal. As for EB34 but 6.3v -Sa heater. 2/6 615 or L63. U.S.A/Osram General purpose triode 6.3v 3a

heater. Va 250v. Slope 3ma/v. Octal base. No top cap.4/6 60B7. Octal base single ended RF peñtode. 6.3v 3a. VA 250.

Slope 4.1ma/v. Used as RF or IF amplifier. 4/6 896G. Octal base 6.3v .45a output pentode. Va = Vsg = 250º..

Watts output 4.5w. 10 watts in class AB push pull. (Can be supplied in matched pairs). 7/6

707. Loktal base 6.3v 16a " straight " RF pentode. Slope 1'3ma/v. 3/-

12A8 Octal Base output. pentode. 12.6v .15amp, Va = vsg 250v. Watts output, 3.4. 8/8

12%8 Octal base beam triode hexode. 12.6v '15amp. Useful as frequency changer up to 45me/s. 818

12SR7 Octal base single ended double diode triode. 12.6v 15. Amp factor 16. Slope 1'9ma/v. 416

210LF 2v lamp battery general purpose triode. Will make useful amplifier or detector valve. 2/6

210VPT. Battery 2v -lamp " Vari -Mu" RF pentode. 7 -pin base. Top anode. 3/-

954. " Vari -Mn " acorn RF pentode. Mounts by stiff wires in glass ring seal. 6.3v 15amp. Useful up to 400mc/s. Slope. 1.4ma/v. 7/8

955. Triode Counterpart el above. 6.3v 15amp. Slope 2'2ma/v. Will oscillate up to 750mc/s. 81 -

SPECIAL OFFER RCA 813. The well-known and well-behaved large trans-

mitting pentode, giving an unmodulated output of 260 watts and 'phone output of 175 watts per valve. 10v ta filament. 2,000v anode. 400v screen. 120 average bias. Brand new in makers' boxes. Limited quantity only. each 57/8

CARRIAGE AND PACKING ON EACH VALVE IS 6d. PER VALVE AND 3d. EXTRA FOR EACH ADDITIONAL VALVE. Shop hours Mon/Fri. 9.00 to 5.30 -Sacs. 9.00 to 1.00

THE "AMBASSADOR" 100

Here is an up to the minute 100 -watt CW and telephony transmitter specially designed for Amateur use.

THE TRANSMITTER. Comprises three self- contained units, RF Unit, Modulator Unit, and Aerial Matching Unit.

R.F. UNIT. 6L6 crystal oscillator as triter or straight crystal oscillator into a 6V6 buffer frequency doubler driving two 807's in push-pull class C.

MODULATOR UNIT. High fidelity modulator (high impedance) for crystal microphone into 6SJ7-615-(2) 807's, output 60-70 watts.

AERIAL MATCHING UNIT. Input impedance (75 ohms) can be changed into any value of continuously variáble output impedance from 15-2,000 ohms. Built in relay from transmitter to receiver. All amateur bands, 3.5, 7, 14, 21, 28 mcs are switched, including the final, with ceramic switches.

All panels 10-SWG Duralumin

Price £140

TELE -RADIO (1943) LTD. 177A EDGWARE ROAD, LONDON, W.2 Phone : - AMB 5393. PAD 611615606


M. & J. PEARSON 373 EGLINTON STREET, GLASGOW, C.5

SPECIAL OFFERS Receivers B.C. 455B. 6 -Valve S'Het, covering 28 to 41 Mgs. Valve sequence. 3 12SK7. 12SR7GT, I2K8 and I2A6GT. In new condition, only 50/- ea. The set has neither power supplies, nor loud speaker, and is also available covering 6 to 9 Mgs. 12 -Valve American I.F.F. Receivers, 30/- each. Receiver RI 124A, new and boxed, 35/- each.

Meters Ferranti. 0-500 micro -ammeters, Grade I, moving coil, 2f" flush mounting. New and boxed. 16/6 each. 0-100 Micro -ammeters, 2f", flush mounting, calibrated 0-1,500 yds. New and boxed. 20/- each. 0-300 Volts. A.C. 2f" flush, moving iron type. New and boxed. 8/6 each.

Condensers Block Type. I plus I mfd. 3,000 volt, 2/6 each ; 800 mfd. 12 volt, 2/- each ; 8 mfd. G.E.C. 600 volt, in boxes of 2, 6/6 box ;

4 mfd. 1,500 volt, 4/- each ; 4 mfd. 450 volt, 2/6 each.

Electrolytiçs 4 mfd. 450 volt, metal 25 mfd. 25 volt, cardboard ; 75 mfd. 50 volt, bakelite. All 10/- half -dozen, £41101- half gross, £8 per gross. These will be mixed as ordered. Tubular : I 350 volt, 5/- doz., 20/- half gross, 35/- per gross.

I mfd. 1,000 volt, 9/- doz. 25 mfd. 350 volts, 5/- doz. I mfd. 450 volt 8/6 doz. Tag Type : 01 mfi., mica, 7/6 doz. 75 P.F., 3/6 doz. Variable : 3 -Gang short-wave type, 5/- each ; 2 -Gang with Steatite base, 5/-. Midget 2 -Gang, one moving vane in each section, 2/6 each 4 -Gang, 00025, 6/6 each.

Miscellaneous A.C. Eliminators 230 volt input, 120 volt output, at 30 m.a. New, only f2/-/- each. Battery charges, all metal rectifiers, input 230-240 A.C. Output, 15 volts at 5 amps. With ammeter and sliding control, only f4/4/- each, 3 m¡m Sleeving, I I /- per reel of 190 yds. 2 m/m Peribraid 9/6 per gross yds.

TERMS We pay all carriage (Gt. Britain only), and Cash with Order, please.

No lists issued.

OPPORTUNITIES IN RADIO

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BRITISH INSTITUTE OF ENGINEERING TECHNOLOGY

149 Shakespeare House, 17-19 Stratford Place, London, W.1

RF Units, Types 24 and 25, complete, 3 stages, 12/6,

RF Units 27 (see Short Wave Magazine, May). complete, 27/6.

GEE Receivers, designed for use with above units, 7 SP6I 7 mc IF stages and rectifier, 55/-. R1155 Receivers, all air -tested, £7/10/-. R1124 Receivers, 6 -valve S'hets, with six switched frequencies, 30-40 mc, 7 mc, IFs, 23/-. R1466 Receivers. As above, but butterfly variable condensers and vernier dial, 30/-. IF Units 34, 12 EF50, 807, etc., 50/-. IF Units 37, 10 EF50, 3 EB34, relays, etc., 50/-. Cathode followers, 3 807, 5U4G, 180-230v power supply, 50 cycles, fully smoothed, 80/-. Wave -form generators 34, 6SP61, 2E1334, 2EF36,

2EBC33, V872, etc., in ventilated metal case, 38/6. RI125 Receivers. 2 stages preset on 38 mc, 15/-.

Rotary Converters. All types, from 10/-. W1117 wavemeters, 125 kc-20 mc, 75/-. HRO power pack, 6v DC input, desk model, 50/-.

And hundreds of other surplus items.

G.S.V. CO., 142 WESTMOUNT ROAD,

ELTHAM, S.E.9

ELT. 6050


TYPE B.C. DUAL FREQ. UNIT

GIVING 100 kcs

ZERO TEMP. CO/EFF.

OR 1000 kcs

LOW TEMP. CO/EFF.

PRICE £3 . 0 . 0

TYPE S

FOR ALL AMATEUR RANGES

LOW TEMP. CO/EFF. CUTS

PRICE £I . 12. 6

7/6 extra for specified freq.

BROOKES CRYSTALS LTD.

IO STOCKWELL ST., LONDON, S.E.IO GRE 1828-0410.

NOW IS THE TIME TO BUY TRANSFORMERS. Ex-G.P.O. Transformers for

rewind, 250 watt with laminations and wire, 25/-. B.T.H. Transformers, 200-230-250 volts 50 cy input, 2 volts 20 amps and 75 volt 6 amps, with 15 taps output, 70/-. Metal Rectifiers, 75 volts 6 amps, f4/10/0.

HAND MAGNETO GENERATORS. Ex-G.P.O. stock, as new, 4 and 5 magnet type, 120 volts 50 ma in wood case, 12/6.

HEADPHONES. Low resistance for Circuit testing etc., single with headband and cord, 3/6 or 5/- pair. High resistance 15/ -per pair with headband and cord.

SOLENOIDS. Powerful electro magnetic type, No. I. D.C. pot magnet with screw -in solenoid core, weight I lb. 10 oz., 2f" x I*", for use on 6-25 volts, will lift 7-28 lb., 4s. each. Type No. 2 has three separate windings, 4s. 6d. each. Solenoid coils of enamelled wire 27 -gauge, weight 6 oz., 2s. each.

TERMINAL BOXES. Polished black bakelite, 3f"x2fff"x2f", with f" centre fillet and screwed cover. 2 -pole, 5/16" connection studs and nuts. Admirable terminal or branch top on large Trans- former, wall or ceiling fixing, 10-50 amps, 2s. 6d. each, or 20s. per dozen.

DIMMERS. Midget enclosed bakelite case dimmers, 100 ohms, f amp, 50 ohms, f amp surface pattern for valves, small light controls or safety control on test circuits. Neat and strong, 2s. 6d. each. 10 ohm I amp porcelain, 2/6.

RELAYS. Ex-G.P.0 30 ohm, 500 ohm, 1,000 ohm, 2s. 6d. each. No. 6 Telephone type, 2 -coil polarised S.P.C.O., 6 volts, 25 m.a., 325 ohms, 5s.. No. IA, S.P. on -off, 2 volts, 2s. 6d.

Please include postage for mail orders.

ELECTRADIX RADIOS 214, Queenstown Road, London, S.W.8

Telephone : MACaulay 2159

Special Offers by CHARLES BRITAIN (RADIO) LTD. RECEIVER TYPE II32a

Brand Spanking New, in maker's original crates. Frequency coverage 124 to 100 me/s. Complete with 10 valves, S meter, in handsome metal case with slow motion dial. Power supply required, 200v HT, 6v LT. A really first-class UHF Communi- cations receiver for only £419. plus 10/-

, 7 6 carriage.

INDICATOR UNIT TYPE 182a

Contains CR tube VCR 517c and 8 valves, 3 EF50, I 5U4, 4 SP6I, 11 Volume controls, and numerous condensers and resistors. The tube used in this Unit is suitable for scope or television if the EHT voltage is kept low ; it is a 6 in. tube and has the same base connections as the VCR97. Amazing 39 L to callers only and we will bargain at /V demonstrate each tube.

R.F. UNIT TYPE 24 AND 25

U.S.W. converters contains 3 SP61, 5 -way 3 -bank Ceramic Yaxley Switch, 7 me/s I.F. output. Tuning ranges, type 24, 20/30 me/s, post type 25, 40 to 50 me/s. Price 6/6 free.

RI124 RECEIVER Suitable for conversion to the television sound channel. Frequency range 30/5 to 40/5 me/s, switched by Yaxley Switch, 5 -bank 6.way. Complete with 6 valves as follows : 3 9D2, 1 8D2, I 15D2, I 4D1, screening cans, ceramic valveholders, 30 resistors and 3 pot meters. Case size 16"x 10"x 16".

Price 19/6 plus 3/- carriage and packing.

R.F. UNIT TYPE 26 AND 27

Contains 2 EF54, I EC52 (RL7) and (RL16) and is a more up to date version of the converters types 24 and 25 described above 27 L post with a slow motion dial. Price i /® free.

BRITISH I.F.F. UNIT Contains 10 valves, Motor Generator and a host of other useful Pricerr J / carriage and components.packing, 7/6.

INTER -COMMUNICATION AMPLIFIER, TYPE 1134A

For battery operation, complete with two valves, types QP2I and 21OLF

I 9 L post

in wooden transit case. Price L/6 free.

SEND FOR LIST S.W.

CHARLES BRITAIN (RADIO) LTD. RADIO HOUSE, WILSON STREET, LONDON, E.C.2 9I


CLVIJESIJALE The Radioman's Shop For Bargains in Ex -Services

Electronic Equipment

BRAND NEW in maker's sealed wrapper

Ex-U.S.A.A.F.

Jefferson -Travis Synchronous Vibrapack U.F.I. Complete and self- contained vibrator Power unit for 12 volts input, output .150/120 volts 30/50 ma. choke/capacity smoothed, L.T. and Bias, plus 44. feet screened input lead fitted with crocodile clips, with circuit in metal case, 7"x4f"x6" finish black.

Clydesdale's price only 19/6 each Post paid

BRAND NEW in maker's sealed cartons

Ex-U.S.A.A.F.

Mallory

Synchronous

Vibrapack

Input 12 volts. Output 150/120 volts. 30/50 ma. Complete unit as illustrated totally enclosed and fully screened. Dimensions 5-1"x2*"x5".

Clydesdale's price only 12/6 each

Post paid

BRAND NEW EX-R.A.F. High Impedance Headphones (S. G. Brown) total imp. 4,000. Ask for S.W.M. I. Clydesdale's Post

price only 7/6 per pair paid Two pairs for 12/6

BRAND NEW Ceramic Wafer Rotary W/C Switch 3 Ceramic (Wearite type) Wafers. 5 positions Single Pole each. Overall length 8" x 4" wide. Ask for S.W.M. 2. Clydesdale's Post price only 3/ I I

each paid

Ceramic Coil Formers I*" x á" serrated edge. Dia. of centre g'. Ask for S.W.M. 3.

Clydesdale's zJ Post price only UU. each paid

4/6 Doz. BRAND NEW, in maker'scartons. R.F. Unit, Type 26 For 50/65 mcs., condenser tuning. Makes an ideal 5 and 6 metre converter, see last month's S.W. Mag. Act now, only a few available. Clydesdale's Post price only 35/ each paid

Magnetic Keying Relay Type 85 For TI 154 Tx. operating speed in excess of 25 w.p.m. 3 solenoids, 6 pole c/o for 6 volts. 7*" x 3=" x 3!". Ask fora S.W.M. 4, Clydesdale's Post price only 5/6 each paid

BRAND NEW 12 volts 75 A.H. accumulator in Waxed Teak box with hinged lid, metal carrying handles at side. Wing nut terminals with connections brought out to 2 -pin socket. Size 16z"x8"x I1á" high. Clydesdale's Lr Packed in a wood

price only box. Carr. paid BRAND NEW Accumulator Charging Switch Board For up to 50 volts, 1,260 watts. Complete, with circuit and connecting data. Contains 6 Meters, 4/0-20 amps, 1 /0-40 amps, /10-50 volts. 5 Heavy Duty slider resistances, 4 charging circuit 12 amp. I voltage regulating, 5 -way control switch, 3 circuit switches, 5 Slidelock fuse holders with fuses, 2 Cut-outs, 8 H.D. Terminals, etc. Enclosed in metal cabinet, with hinged doors and fixing feet. Dia. 20"x 18"x8". Clydesdale's Carriage price only 63/- each paid

Packed in a wood case.

FOUNDATION METER. Moving Coil.

Brand New in maker's boxes. Scale marked. 0/5000 ohms.

0/60 ma. 0/1.5 volts. 0/3 volts.

5 ma Movement, resistance 250 ohms. 2;" Round white scale, flush mounting. Clydesdale's y Post price only 17/6 /6 each paid

BRAND NEW, in maker's carton. Engine Driven Generator Supplies 24 volts, 1,500 watts, at 5,000 r.p.m. Rotation of shaft clock- wise, cooling airducts, four -bolt fixing flange, totally enclosed in cylindrical metal case 13"x 6" dia., length of coupling shaft I", weight 37 lb. Clydesdale's Carriage prick only 71//'` each paid

R.F. Unit, Type 24. 26-30 mcs.

With switched position tuning. Brand New, in maker's cartons. Clydesdale's Post Price only 1 9/6 each paid

Used, good condition. Clydesdale's q Post

price only 1 2/6 each paid

Send now for New Illustrated Lists. Please print Name and Address

CLYDESDALE SUPPLY CO LTD GLASGOW - C.5

2 BRIDGE STREET

'Phone : SOUTH 2706/9 VISIT OUR BRANCHES IN ENGLAND, SCOTLAND AND NORTHERN IRELAND


AN AMERICAN PUBLICATION

coThe Radio Amateurs' Journal

NO " HAM " SHACK IS COMPLETE WITHOUT G° CQ "

"CQ ". is published exclusively for the AMATEUR and SHORT WAVE

Listener. Each issue contains large feature articles on the construction of Transmitters, Receivers, Modulation Equipment, Aerials, etc., etc. Dozens of photographs

and illustrations.

SUBSCRIPTION FOR ONE YEAR 17/6 Post paid (Published Monthly)

We have made arrangements for subscribers to receive copies of this famous American Magazine direct from the Publishers immediately each issue comes off the press. NOTE: We can supply by return of post, RADIO HAND- BOOK, 17/6, and the latest RADIO AMATEURS' CALL BOOK, 10/9 Post Paid.

Post your "CQ" subscription to -day to :

DALE INTERNATIONAL Publications Limited,

105 BOLSOVER ST., LONDON, W.1. Telephone.: MUSeum 1023.

Q.C.C.

TYPE P5

QUARTZ CRYSTAL

U NIT This unit uses the well-known Q.C.C. Power type crystal, which is undoubtedly the most rugged and active crystal cut available for amateur use. The crystal is mounted in our type U dust -proof holder, with standard * in. pin spacing, as illustrated above. The P5 unit has a temperature co -efficient of 20 cycles per megacycle per degree Centigrade temperature change. Used with a 6V6 or 6L6 type beam tetrode, it will give up to 5 watts r.f. output on the fundamental frequency and approximately 3 watts on the second harmonic in the Tritet circuit. Available with fundamental frequencies in the 1.7, 3.5 and 7 Mc. bands for fundamental operation or frequency multiplying to any higher frequency band. An official certificate of calibration is sent with each P5 unit, giving the frequency under stated operating conditions to an accuracy of 0.025%.

PRICES : Ground to your specified frequency in the above bands . £1/17/6

Or ground to a frequency not specified by you but taken from our stock ... ... £1 /12/6

Please note that all the leading dealers in amateur equipment now carry stocks of the PS crystal unit. THE QUARTZ CRYSTAL CO., LTD. (Directors: E. A. Dedman, G2NH., N. H. R. Munday, G5MA., W.J. Thompson, G2MR), 63/71 Kingston Road, NEW MALDEN, SURREY. Telephone : MALden 0334

RADIO CLEARANCE LTD. 27 TOTTENHAM COURT ROAD, W.I. 'MUS 9188

ANOTHER BARGAIN 6 -VALVE RECEIVERS

Line Up ! 12SK7 R.F., 12KB Mixer, 2 !.F.s, 12SK7, DET and B.F.O., 12SR7, Output, 12A6. Available in 2 types : 1, Covering 190-550kc/s with 85kc/s I.F. 2, Covering 6 I-9mc/s, with 2.8 me/s I.F.s. The size, II" x 5" x 5f", identical in both cases. These sets were operated from plug-in 28v dynamotors. Ideal for use as double super-hets (the Q Fiver of Jan. Q.S.T.), conversion to car radios, Type 2 as 40mte REC or with R.F. units 24-27. Supplied complete with valves, less dynamotor, at the Bargain Price of 39/6. Postage 1/6 extra.

TRANSMITTER POWER PACKS Input 200/250v 50c/s. Output 1200v 200mA, with metal rectifiers and smoothing. Enclosed in perforated metal case 19f"x94"x 17", £4/10/- carriage paid.

R.F. UNITS TYPE 27 3 -valve converters using V.R. 136 R.F., V.R. 136 Mixer, V.R. 137 Osc., range 60-80 me/s. Makes very useful 58 me/s converter, when modified. 27/6 with valves.

Rí481 RECEIVERS We still have some of these sets brand new in transit cases, Freq. range 65-86mc/s, IO valves, R.F. VR65, Osc. VR66, mixer VR65, 3 I.F.s, VR53's, Det. and A.V.C. VR54, AF, VR57, output VR67, B.F.O. VT65, VS70 (stabiliser on ost.). I.F. I2mc/s, built-in tuning meter, R.F. and L.F. gain controls, 6" S.M. dial. Requires power (250v, 50mA, 6.3v, 4A). These receivers lend themselves readily to modification for 5 metres, F.M., etc. Supplied, complete with all valves, and circuit diagram. The price, £7/19/6. Power packs, for above sets, 19" rack mounting, available only with sets at £2/19/6.

Moving Coil Meters, Metal Cases 500mic/A F.S.D. Scaled 0-10, 14" Circular, 5/-. 500mic/A F.S.D. Scaled, 0-500, 2" Circular, 8/6. 500mic/A F.S.D. Scaled 0-15v, 2" Circular, 7/6. 500mic(A F.S.D. Scaled, 0-600v, 2" Circular, 7/6. 20A F.S.D. Scaled, 0-20, 2" Circular 5/-. 40A F.S.D. Scaled, 0-40, 2" Circular, 5/-. R.F. Units, Type 24 and 25 5 switched frequencies, 24 30/40 me/s, 25 40/50 me/s. 3 valves (VR.65's), R.F., Mixer, Osc., I.F. 7.3 me/s. 3 -bank ceramic switch complete with valves, 16/6.

Moving Coil Meters, Bakelite Cases 0-1mA 2" square, 7/6. 0-30mA 24" circular 7/6. 0.150mA 2" square, 8/-. 0-3A R.F. 2" square, 6/-.

0-300V, 2" square, 7/6. (With series resistor provided)

0-500mA, 2f" circular, 19/6d. 0-4A R.F. (Thermo- couple) in rectangular case 2f"x3f"xIf", with push button short switch incorporated 8/6. 0.6mA, 2f" circular, calibrated 4 scales : 0-1.5V, 0.3v, 0-60mA, 0-50002 12/6. Visual Indicators Crossover needle type 2, 60mA movements 5/I1.

228. SHORT WAVE MAGAZINE JUNE 1948

VALLANCE'S FOR VALUE HEADPHONES H533. An extremely sensitive pair of lightweight headphones with an impedance of 600 ohms, and made by Western Electric. These phones are ideal for crystal sets or receivers with low impedance output. Suitable for high impedance output with 4-1 (approx.) transformer. Complete with ear -pads, leather headbands, headphone cord and jack plug. Price 3/9d.

MICROPHONES, LARYNX. This carbon throat type mike is a lightweight, compact unit and is complete with fixing strap cord and miniature plug. Microphone Unit MC -254-A. This was originally designed for use in aircraft oxygen masks, and is an

extremely sensitive carbon unit. Price I/5d. both types.

TAYLOR ALL -WAVE SIGNAL GENERATOR 65B. A mains -operated, portable Signal Generator covering the frequency range 100 kc/s to 46 megs. Designed for general radio frequency test work, this instrument is suitable for tests on radio receivers ; ganging and alignment, adjustments on tuned circuits and as a

standard of radio frequency. A 400 c/s audio signal is available for testing audio amplifiers and audio sections of radio receivers. Price £15/10/- or an initial payment of £I/I0/2d. and II payments of £119/8.

500 -volt WEE-MEGGER TESTER. Resistance can be measured very simply by means of a Megger Insulation testing set, which indicates directly on a scale the insulation resistance of the apparatus or insulation under test. Excellent for testing house wiring, motors, etc., and has a range up to 20 megohms. Price £13/16/3d.

TRANSMITTING VALVES. RK34 20/-, PT15 32/6d, 866 27/6d, TTII(min 807) 20/-, GU50 25/-, 35T 63/-, KT8C 25/-, GUI2 32/6d, U19/23 33/Id, DA4I 55/-, 829 21/-.

ELSTONE OUTPUT TRANSFORMERS, P.A. Series. All transformers in the P.A. Series are fully inter- leaved, essential when pentodes are used in the output circuit. Sectionalised windings are employed to ensure minimum leakage inductance, necessary to maintain top -note response. Generous core cross section of high permeability steel is used, ensuring a maximum value of inductance with a minimum amount of distortion below 150 cps.

TYPE MR/7. Rating 7-10 watts, Heavy duty. Fitted with terminal panel. Ratios available 100-I, 100-ICT ;

66-1, 66-ICT ; 44-1 44-ICT ; 36-I, 36-ICT; 33-1;

26-I, 26-ICT; 25-1 ; 22-1 ; 19-1 ; 18-I ; 14-I. Price 18/9d.

TYPE MR/I5. Rating 15-18 watts. All ratios available. Single -ended or Push Pull, 13, 16, 18, 20, 22, 27, 33, 40, 52, 66 and 80/1. Primary loading 2,000 to 16,000 ohms. Secondary impedance I to 30 ohms. Maximum primary current for single ended 90 mA. For Push Pull, 100 mA in each half of primary. Price 41/6d.

TYPE MR30. As above but maximum rating 30 watts. Primary current for single ended 170 mA, for Push Pull 170- mA each half primary. Price 49/6d.

TRAIN TRANSFORMERS. This transformer is designed for use with model engines and has the following rating, 220 volt AC input and 20 volt 1.5 amp output. Dimensions 3";;3"x3". Price 45/-. Only a few available.

SPEAKER FIELD REPLACEMENT CHOKE. This Surrey type SC5 will replace the 2,000 ohms field of a mains energised speaker, when it is being replaced by a Permanent Magnet Speaker. The choke is rated at 150 Henries. 70 mA max. Price 17/5d.

DENCO COIL TURRET. CT6, This turret is designed for a superhet receiver using a triode hexode or similar mixer valve and an IF frequency of 465 kc/s. Frequency coverage is from 15

to 30 megs, with exceptional short wave performance. The unit includes complete dial and drive assembly, twin gang tuning condenser with necessary padders. The coils have their own dust cores. - The use of polystyrene insulation throughout, with silver-plated contacts and High "Q" coils, ensures a very high performance. Price £4/19/6d.

DENCO COIL TURRET CT/4. A three -section tuning unit fur a communication or advanced superhet receiver employing one RF and a triode hexode mixer stage, with an IF frequency of 1.6 megs, this turret supersedes the CT3. Frequency coverage is from 15 to 42 megs. All tuning, padding, and parallel trimming condensers are incorporated in and selected by the turret. The main dial is of the rotating type, to be used with cursor supplied with the turret, and will have direct calibration of five amateur bands. By ingenious means the turret has been designed to give stable operation with the new high slope miniature valves, so that the performance on the highest frequency range is equal to that of the low ones. A gain of 20db is obtained in the RF stage. Place your orders now to avoid disappointment.

Delivery 3 to 4 weeks.

Speedy Postal Service C.W.O. or C.O.D.

Valiance & Davison Ltd 144 BRIGGATE, LEEDS I Phone: 29428/9

Staff call signs :-G2HHV, G8SX, G3ABD, G3AHV

INDEX TO ADVERTISERS

Page A.C.S. Radio 282 Amateur Radio Service 279 Automatic Coil Winder 217 B.I.E.T. 224 Barnes Radio 285 Belling & Lee 275 Berry's Ltd. Cover iv Brighton Trade Services 287 Britain (Radio) Ltd. 225 Brookes Crystals Ltd 225 Brown, S. G 275 Bulls, J 286, 288 Candler System 287 Celestion 219 Clydesdale Supply Co. Ltd. 226 Coulphone Radio 288 Dale International 227 Davis, Alec, Ltd. 223 Electradix Radios 225 Export Disposals 279

General Products 278

General Sound & Vision Co. 224 H.A.C. Short -Wave Products 287 Holle, A. C. 284 H.P. Radio Services Ltd. 286 Henleys 277 Instrument Co 222 Johnsons 283 London Television Co. 218 Lyons Radio 220 M.O S Cover iii Merribuil Products 288 Odeon Radio 219 Pearson, M. & J. 224 Premier Radio 276 Pullin (M. & I.) 221 Quartz Crystals 227 Radford, Arthur H 283 Radio Clearance 227 Radio Exchange 281 Radiovision (Leicester) Ltd. 218 Rainbow Products 284 Samsons Surplus Stores 278 Short Wave (Hull) Radio 282 Small Advertisements . .. . 281, 288 Smith, H. L 286 Taylor Electrical 230 Tee, Herbert 280 Tele -Radio (1943) Ltd. 223 Torbay Elec 285 Trading Post 279 U.E.I. Corp 222 University Radio 288 Valiance & Davison Ltd. 228 W.B. Radio 281 W.D. Sales 220, 281 Webb's Radio Cover ii Whitaker, H 277 Woden Transformers 221 Young, C. H 280

Mention the Magazine

when writing to

advertisers- It Helps You,

Helps Them and

Helps Us

SHORT WAVE MAGAZINE

FOR THE RADIO AMATEUR & AMATEUR RADIO

Vol. VI JUNE 1948 No.59

CONTENTS Page

Editorial 231

Single-Sideband Suppressed Carrier by J. Wood (G3VG) 232

Transitron VFO finit by A. G. Wood (G5RZ) 235

Two -Stage Battery Transmitter by C. Finch (G3AHO) 237

Steel Lattice Mast by F. N. Bedwell (G8DT) 238

BCI from 1.7 and 3.5 me by G. C. Turner (G5IH) 240

Going Portable by The Old Campaigner 241

DX Commentary by L. H. Thomas, M.B.E. (G6QB) 246

Twenty -Metre DX Forecast by I. D. McDermid, A.R.T.C. (GM3ANV) 252

Simple Break -In System by R. J. Donald (G3DJD) The VHF Bands by E. J. Williams, B.Sc. (G2XC)

British Old Timers' Club

Superhet for 420 me by G4L U

Grimsby Occasion Eddystone " 640" Presentation

Here and There 267

New QTH's 268

Other Man's Station-ZD4AM 270

Month with the Clubs From Reports 271

253

254

261

262

266

Editor: AUSTIN FORSYTH, O.B.E. (G6FO) Advertisement Manager: P. H. F AL K N E R Assistant Editor: L. H. THOMAS, M.B.E. (G6QB)

Published the first Wednesday each month at 49 Victoria Street, London, S. W.1. Telephone: Abbey 2384. Annual Subscription: Inland 20s. Abroad 22s. post paid.

Copyright Reserved throughout the World

AUTHORS' MSS. Articles submitted for editorial consideration must be typed double-spaced with wide margins, on one side only of quarto sheets, with diagrams shown separately. Photographs should be clearly identified on the back. Payment is made for all material used, and a figure quoted in the letter of acceptance. It is a condition of acceptance that copyright of all material used passes

to the Short Wave Magazine, Ltd. on publication.

THE SHORT WAVE LISTENER ASSOCIATED WITH THIS MAGAZINE IS SPECIALLY FOR THE RECEIVING ENTHUSIAST


Announcing ... the Neira. Taylor Cathode lay

Oscillograph

MODEL 30A PRICE £29 10 0 H.P. TERMS : £2 17 0 deposit and 11 monthly payments of £2 16 6

DELIVERIES HAVE NOW COMMENCED Obtainable from your local dealer or direct from the manufacturer

TAYLOR ELECTRICAL 412.424 MONTROSE AVENUE,

This instrument is a general-purpose oscillograph using a 3k -inch tube. A linear time -base generator and a push- pull vertical amplifier are incorporated.

CATHODE RAY TUBE. A 3k -inch tube having a green fluorescent screen and electrostatic deflection is used in this instrument.

AMPLIFIER. A push-pull amplifier for the vertical plates is fitted and provided with a switch to give ratios of 1, 10 and 100 in amplification. The amplifier is designed to cover the audio frequency range, and useful amplification is available up to 100 k/c.

LINEAR TIME BASE. A linear horizontal time base is provided with coarse and fine frequency controls covering a range of 10-10,000 c.p.s. A switch and adjustable control enable the time base to be syn- chronised either .externally or to the mains supply frequency or by the signal applied to the vertical amplifier.

SINUSOIDAL SWEEP. Provision is made for horizontal sweep at mains frequency. This enables quick identification of mains hum.

CASE. This instrument is mounted on a steel panel and fitted into a steel case. Both panel and case are finished in black crackle.

POWER. The oscillograph is operated from A.C. mains, 110 or 200-250 volts A.C., 40-100 cycles. Consumption is 25

watts.

DIMENSIONS. 15¡ by 124 by 74 in.

WEIGHT. 24 lb.

TABOR PRODUCTS INCLUDE MULTIRANGE A.C. D.C. TEST METERS SIGNAL

GENERATORS VALVE TESTERS A.C. BRIDGES CIRCUIT ANALYSERS

CATHODE RAY OSCILLOGRAPHS HIGH AND LOW RANGE OHMMETERS

OUTPUT METERS INSULATION TESTERS MOVING COIL INSTRUMENTS

INSTRUMENTS LTD Weeps SLOUGH NSSI r4 awl

SLOUGH. SUCKS, ENGLAND, Gram. & C.SH.. TAXWE ° SLOUCH


EDITORIAL

Perspective In this space two years ago we discussed the law of the penny bun-it cari only be sold at a penny if the demand for it is such that it can be manufactured profitably for a halfpenny. The situation now is still much as it was then, in spite of the rosy prospects held out for the future by mis- guided individuals who, if they had not forgotten anything, had certainly learnt nothing. Price is, however, becoming more of a factor now than it was two years ago, and we are also beginning to see the expected contraction of the British radio industry ;

this is partly due to the artificially restricted home market (the pressure of a high purchase tax) and partly because of reduced and much more difficult export sales (market saturation and intensified foreign competition) .

Though these trends are inevitable and must occasion wide misgiving and anxiety for the future in the set - making section of the industry-which represents probably 8o per cent. of British radio manufacturing capacity as a whole it need not yet occasion any deep concern for those manufacturers catering for the specialised markets. These include equipment for railway, police and fire services at home and abroad, for the great Government research programmes, for the tremendous commercial development of electronics in a large number of new applications, and to a lesser but none the less important extent for the highly specialised and individualistic Amateur Radio market. It may well be that in the long run amateurs will benefit by the availability of equipment suited to their needs at prices lower than ever before-because with the coming technical development in the art of Amateur Radio much of the demand in our field will be the same as the requirements in the new fields of commercial electronics.

tic)/4f_,5


Single-Sideband Suppressed Carrier An Outline of the System, and Its Possible Amateur Application

By J. WOOD (G3VG) (Post Office Engineering Department, Radio Branch)

HE article on Single-Sideband Sup- pressed Carrier (S.S.S.C.) working in

QST for January seems to have aroused some interest in this subject amongst amateurs and prompted the writing of this paper.

The principle of Single-Sideband transmission is not new-it has in fact been in constant use on British commercial circuits since as long ago as '1925.

At that time it was in its simplest form and only operated at very low frequencies -the first application being Trans- atlantic S.S.B. telephony on a frequency of 60 kc. A great deal of development has taken place since then, and there are now several systems in use. The principal systems are classified below :

DOUBLE CHANNEL - SUPPRESSED CARRIER SINGLE CHANNEL - SUPPRESSED CARRIER SINGLE CHANNEL - CARRIER UNSUPPRESSED

Double channel

Suppressed carrier

Suppressed carrier at say 10 me

Chan. "A" Chan. " B "

j///////\\\\\\\\\\\

9994 kc 10,000 kc 10,006 kc

Separate transmission on each S;'B

Single channel

Suppressed carrier 9994 kc

Single channel

-Plus carrier

Filtered out S/B

i J //////!/i

10,000 kc

Normal carrier

% 9994 kc 10,000 kc

Filtered out S/B

Fig. 1. Frequency spectrums of ` single-sideband suppressed carrier systems. In each case a band -width of 6000 cycles is desirable for high-fidelity transmissions. This can be reduced for acceptable quality speech trans-

mission.

Some preliminary notes on the subject were given in our issue for February, 1948. Here is a fuller description of what the S.S.S.C. method of telephony transmission actually entails from the practical point of view. We might also add that, for all the publicity S.S.S.C. has had on the other side of the Atlantic, it is-like most other radio developments of fundamental importance- entirely a British system of commercial telephony working. As such, it has been used by our GPO on certain of their radiophone circuits for 20 years.-Ed.

The various frequency spectrums of the systems mentioned are shown and will help to clarify the definitions. (See Fig. 1).

In the Double -Channel systems separate intelligence is conveyed on each Side - band, i.e. two separate transmissions. This is achieved by the use of several balanced modulators and filters and d is very complex.

In a normal Double-Sideband Trans- mission (ordinary amplitude -modulated 'phone transmission) the power distribution is as follows :

50 per cent. of total radiated power is Carrier. 25 per cent. of total radiated power is Upper Sideband. 25 per cent. of total radiated power is Lower Sideband.

Since the carrier does not contain the intelligence this is 50 per cent. of wasted power and since only one Sideband is necessary to convey intelligence this is a further 25 per cent. of wasted power. It therefore follows that a saving in power of 75 per cent. can be achieved by the use of S.S.S.C.

The essential components of such a system are :

(1) An S.S.S.C. drive unit, the purpose of which is to generate the system.

(2) A linear transmitter or RF amplifier to amplify the generated S.S.S.C. transmission.

Drive Unit There are in general two methods of

producing an S.S.S.C. signal :

(a) By the use of Filters. (b) Phase -shift method. -

The balanced modulator is used in both methods and a circuit of a typical BM is shown in Fig. 2. It will be seen


Carrier input say 10,000 kc

3 Modulato input say 1,000 cycles

Tuned to carrier frequency

Output containing two

S/B (carrier suppressed)

Lower S/B-9999-10,000 kc Upper S/B-10,001-10,000 kc

Fig. 2. Fundamental circuit of the balanced modulator, an essential unit in the system.

that the'modulation is applied in push- pull,,whilst the carrier is applied in phase. The output is taken from the tank circuit LlLand will consist of several frequencies, being the various sums and differences of the injected component frequencies. If Ll is made resonant at the frequency of the carrier, the output will then consist of the modulation at carrier frequency Fc+Fm and Fc-Fm, the carrier being suppressed. Even -in a well designed B/M the carrier is not completely balanced out but is still present at a level of -50- 60 dB to the Sideband. However, since -60 dB is a power ratio of one in 10° it is to practical purpose balanced out.

The output from the B/M then consists of an upper and lower S/B. This is fed

Amplifier

y Mod input

Both S/B's

ABBREVIATIONS USED IN TEXT S.S.S.C. Single Sideband, Sup-

pressed Carrier. D.S.B. A.M. Fe Fm B/M S/B 01 02

Double Sideband. Amplitude Modulation. Carrier Frequency. Modulation Frequency. Balanced Modulator. Sideband. Oscillator No. 1. Oscillator No. 2.

'nto a band-pass filter eliminating one of the Sidebands. The resultant is the Single-Sideband, carrier suppressed. In practice it is standard to use more than one stage of modulation. This helps to simplify the filtering out of the undesired inter -modulation products. The first carrier injected into the first B/M is preferably a low frequency carrier.

Balanced modulators have a low efficiency and so it is better to generate the S.S.S.C. system at a very low level and then amplify it by using a linear transmitter. The schematic of a typical S.S.S.C. transmitter is shown in Fig. 3.

Advantages of S.S.S.C. The advantages of S.S.S.C. over a nor-

mal AM transmission are outlined below :

(1) Band -width only half as great as with usual AM system.

(2) Multi -path fading greatly reduced. (3) Power economy at transmitter.

Since Tx is Class -B linear there is reduced power consumption when modulation is off.

(4) Signal-to-noise ratio improved by 9 dB ; 6 dB is due to suppressed carrier, and 3 dB to reduction of band -width and consequent reduction of noise.

One S/B

Lower S/B filtered out

At carrier frequency

Fig. 3. Schematic of a typical S.S.S.C. system.

Two S/B Single SIB

Drive to linear Tx


Nine dB is a power gain of 8, so a 150 -watt S.S.S.C. transmitter will produce a field strength equal to a 1.2 kW transmitter using the normal amplitude -modulated system.

Disadvantages Offsetting the advantages one must

bear in mind the ever -constant disadvantages of :-

(1) Complexity of design and construction.

(2) Increased initial cost of equipment. (3) Greatly increased fault liability. (4) The re-insertion of the carrier at

the receiving end must be of the correct frequency and phase with respect to the suppressed carrier. This presents difficulty although in some systems a "pilot'' carrier is transmitted with the S.S.S.C. signal.

Carrier Re-insertion Undoubtedly the biggest difficulty that

will arise in amateur S.S.S.C. transmission is the replacing of the carrier at the receiving end. It will be appreciated that the re-inserted carrier frequency must differ as little as possible in frequency from the original, because the difference in frequency will cause the demodulated intelligence to be that same amount different from the original modulation.

A tolerance of five Drive unit cycles is usual. However, since correct frequency response is not so important in amateur DX working, a somewhat greater frequency difference is per- missible and commercially ground close tolerance crystals could be used with satisfaction.

The phase of the re-inserted carrier with respect to that of the original will not be so important in amateur working and can be neglected completely.

In amateur systems, the re-inserted carrier can be injected into the RF or IF stages of a normal receiver.

Filters The last important obstacle is the design

and construction of the Band -Pass filters -following the B/M stages.

These filters should have a band -pass - width equal to the sideband transmitted -a width of 2,500 cycles is ample for good speech-and must possess sharp cut-off characteristics. The successful design and

construction of such filters is somewhat complicated and will prove an obstacle. A simpler scheme recommended by the writer is to dispense with the filters.

This would also mean that only one stage of B/M is now required. A schematic diagram and circuit of this arrangement appear in Fig. 4. The resultant signal would be D.S.B. carrier suppressed. However, this would still retain some of the advantages outlined earlier-notably the 6 dB improvement in signal-to-noise ratio as a result of the carrier being suppressed.

6 dB is a power gain of 3.9, so this simplified system would give performance equal to a normal 600 -watt transmitter when using a 150 -watt transmitter operated D.S.B.S.C.

Linear Transmitter Finally, a few notes on the transmitter

which is now to operate as a linear amplifier.

The push-pull stages are operated in Class -B. Actually, best results are obtained with the valves biased to "projected

about I-2 watts

RF

Linear Tx

Fig. 4. Schematic of a suggested simplified system for amateur S.S.S.C. operation.

cut off," i.e. slightly less than cut off. The output should be proportioned to input volts and the plate current flows in pulses that are half -sine waves possessing an amplitude proportional to the excitation voltage. The linearity is best checked on an oscilloscope.

The theoretical maximum efficiency of a linear amplifier is 78.54 per cent. and the highest practical efficiency obtainable is 60 per cent. at crest of modulation.

S.S.S. C. will be further discussed in future issues.-Ed.


Transitron VFO Unit Design for a Stable, Directly Keyed Driver

By A. G. WOOD (G5RZ)

HE present crowded state of the amateur bands makes the VFO

almost a necessity, and for the CW man an instrument capable of being used for break-in is also a considerable advantage.

The writer therefore makes no apology in offering details of yet another VFO, especially in view of the interest which has been shown over the air in respect of this particular version. No special credit is claimed for the circuit details ; indeed, grateful thanks are due to many operators for their helpful suggestions during the initial testing period.

The main requirements of a VFO are (a) Extreme stability ; (b) good keying control ; (e) good output, and (d) a good frequency range.

After considerable work on the Franklin and other VFO's the writer has lately developed the pentagrid Transitron oscillator with which it can honestly be claimed that all the points mentioned are fully satisfied. Into the bargain, the results have been achieved with considerable economy in valves and current load as compared with other types of standard VFO circuit.

Circuit Arrangement As will be seen from the circuit diagram

in Fig. 1 the pentagrid in use is a 6A7, but it is believed that the 6A8 would serve equally well with the added advantage that the latter has the standard 8 -pin base. The output from this oscillator is fed into the grid of a 6V6 which is arranged to operate in Class -A. This point is important so that, in theory at any rate, no load is placed upon the oscillator.

In the circuit shown no voltage stabiliser is employed and so free is the note from any semblance of chirp that one is not considered to be necessary. Both the oscillator and its buffer are fed from their own source of power, at 350 volts, and the total current drain of the oscillator is about 11 mA and that of the buffer 20 mA. Since the latter is operating Class -A this current imposes a steady load on the power supply when the oscillator is keyed, which is, no doubt, one reason why voltage stabilisation is unnecessary.

The oscillator and its buffer should be

The VFO as primary drive has come to stay and, indeed, is almost a necessity on the DX bands under present-day operating conditions. In our issue for June, 1947, the Transitron oscillator was described and its application as a particularly stable RF generating source in a driver unit discussed. Though our contributor has employed a TU5B tuner as the constructional basis for his design, the circuit he suggests can be built up in any other

suitable form.-Ed.

well shielded and it is also important to see that the HT and LT power leads are properly screened and kept as short as practicable. Some trouble was experienced at first in getting a true T9 note when driving the PA and there were traces of chirp which were absent when monitoring the oscillator unit unloaded. This trouble was traced to RF feedback in the supply cables and upon screening these and earthing the screen all trouble disappeared. Another point to watch is the cathode by-pass condenser. As will be seen from the circuit, this condenser also parallels the key jack and thus reduces key -clicks to a minimum, the capacity and cathode resistor acting also as a filter.

Construction Constructional design is a matter of

individual taste but details of the writer's model will no doubt be of interest. The VFO and buffer are incorporated as one unit in a TU5B tuner which may still be obtained on the surplus market for a modest 25s. or so. All the internals of the TU5B were removed with the ex- ception of the two tuning sections and the linked switch gear ; this just leaves comfortable room for the installation of the two valves, one on either side of the internal screen. On the front panel (making use of the holes left) were fitted a jack for the key and a toggle switch which cuts HT to the buffer ; this is also employed when adjusting the VFO frequency for subsequent operation. The output coupling coil on the buffer tank was reduced to three or four turns and taken through the front of the panel by means of a length of co -ax terminated in a plug. Three -core screened cable is led through


R R2 R3

R7

R4

RS

o si

8R SZ RFC

C9

C6

HT -f- 350y

LINKTO DOUBLER

HT-

VFO arrangement incorporating a Transitron oscillator and buffer stage. The author's own version is built round a TU5B tuning unit.

Table of Values Fig. 1. Transitron VFO

Cl, C2, C5

C6 (see text) C3, C4, C9 = 01 µF, mica

1 µF, mica C7 100 µµF C8 002 µF RI = 100,000 ohms R2 R3

= =

10,000 ohms, 50,000 ohms

1 watt

R4 = 56,000 ohms R5 = 1;000 ohms R6 = 450 ohms R7 = 1 megohm R8 = 385 ohms

the rear of the screening box for plugging into the power unit. An earth terminal is also provided. The main feature of the TU5B is the excellent slow-motion dial on the oscillator circuit and the temperature -compensated coil inside and so well does this work that scarcely more than a few cycles' drift can be detected on 3.5 me even when starting up from cold. The frequency covered in four switched positions is 1.5 to 3.0 mc and the RF output is more or less constant over the whole of this range.

Operation The writer normally operates the VFO

on the 1.75 mc setting, at which frequency it takes 8 deg. to cover 1 kc.

The 1.75 mc drive is link coupled to the grid of a 6SN7GT twin -triode working within its rated capacity as a push -push

doubler on 3.5 mc and the output from this little valve drives the KT8c PA up to about 25 watts. Somewhat greater drive can be obtained by sub- stituting a 6SL7GT and adjusting the grid bias accordingly and with this about 35 watts input to the PA can be obtained on 80 metres.

In operation the toggle switch on the front panel is cut and the VFO adjusted to the desired frequency by listening to the oscillator harmonic on the operating frequency. In some stations it may be difficult to pick up the 14 mc harmonic, but in the writer's case the VFO unit stands right on top of the receiver and this harmonic is just nicely audible.

Having adjusted frequency a touch on the toggle switch will bring the buffer into operation and the whole transmitter is live the moment the key is pressed.

With a basic range of 1.5 to 3.0 mc many frequency multiplying combinations will suggest themselves to the user ; for example, tripling into 7- mc from 2.333 mc, but as with all UFO units care should be taken to make absolutely certain that the signal is within the band by checking the calibration at frequent intervals against the station standard measuring apparatus.

In conclusion the writer can modestly claim that with no less than 172 QSO's using this unit only 12 were reported as less than T9 whilst 15 contacts gave T9x reports and many add the remark "FB."

"THE TYPE 145 OSCILLATOR" The author of this article in our April

issue, G2NS, points out that as the result of correspondence arising from it, there would appear to be a number of minor variants of the Type 145 in readers' hands. There were apparently certain small modifications to the original design, which may or may not have been incorporated in some units which eventually found their way to the surplus market.


Two -Stage Battery Transmitter Simple Design for No -Mains QRP Operation

by C. FINCH (G3AHO)

JUDGING by the activity on the amateur bands during the power cuts

last winter, it would appear that many stations still use batteries for power supplies, and it was thought that the small transmitter about to be described might prove of interest. The writer is without mains supply and this transmitter, together with a simple 1-V-1 receiver, was used for a long time on 7 mc, during which time many interesting contacts were made.

General Design The transmitter follows conventional

design and no snags should be met in construction and operation. The circuit consists of a crystal oscillator driving a Cossor 230XP in the PA. This valve is a super output triode, and has been driven to 12 watts with 200 volts on the plate- although this, of course, is not advisable for any length of time.

In the writer's transmitter a permanent meter was included with suitable shunts and resistors, switched, for measuring the HT and LT voltage and PA grid and anode currents. But this is, of course, not necessary providing jacks are included in the respective leads and a suitable meter is available having ranges of 5 and 50 mA.

As both sides of the condensers are at HT potential, it is important to make sure that they are well insulated from the panel. All supply leads are taken to a terminal strip at the rear of the chassis.

Adjustment To operate the transmitter, the meter

should first of all be inserted in the grid lead of the PA with HT applied to the CO only ; when the crystal is oscillating a reading will be obtained. Next, the PA should be neutralised, and the method used by the writer was as follows : Insert the PA coil and rotate the PA tuning condenser. On passing through resonance a kick will be observed on the grid milli - ammeter. The neutralising condenser is then adjusted until no movement is

observed when passing through resonance. It may be necessary to retune the CO slightly for maximum grid current during this operation.

When the PA has been neutralised it should be biased to twice cut-off value, and the HT applied. With the meter in the PA HT lead, the PA should now be tuned for minimum current, which will be 3-5 mA, from approximately 40-50 mA when out of tune.

It will be observed that keying is by breaking the HT negative lead, and with a 2 µF condenser across the contacts, no

HT+ 120v - 150v-

NC

VI

210 HL

RFC

C4

V2.

230 XP

C6

Key jack

Circuit of G3AHO's battery CO/PA-simple but efficient. ,

HT-

Table of Values Two -Stage Battery Transmitter

RI = 20,000 -ohm resistor Cl, C2 = .001 µF condensers

NC = Neutralising condenser C3 = 00016 µF C4 = 0001 µF C5=0.1µF C6 = 2 µF

Coil winding data for 7 mc band CO = 18 turns, 20 SWG PA = 25 turns, 18 SWG, centre

tapped

trouble should be experienced with key - thump or chirp.

The writer has only used this transmitter on the 7 mc band, but there is no reason why, with suitable coils and crystal, it should not be used on other bands.

As regards results obtained, some excellent contacts were made with many European stations with a maximum input of 5 watts, although mainly the input was in the region of 2-3 watts. The best DX was Italy, with 5 watts input.

238 SHOAT WAVE MAGAZINE JUNE 1948

Steel Lattice Mast Self -Supporting Structure for

the Rotary Beam

By F. N. BEDWELL (G8DT)

HE mast to be described can be easily constructed with a little patience.

It can be built up on the ground and hoisted after completion with the help of three or four persons. It is strong enough to hold a 10 -metre rotary beam and will withstand rough weather without guying.

The materials required are :

Eleven 18 ft. lengths of 14 -in. X i -in. angle iron ; 300 -ft. of 1 -in. X i -in. mild steel strip.

The bolts throughout are 1 -in. X i -in. BFS, HS, as these are much stronger than mild steel. The total cost is about £8 and the writer had no difficulty in obtaining this material.

General Design The mast is on a base 5 -ft. square,tapering

to 9 ins. square at the top, and is 32 -ft. 6 -ins. high. The top section forms a square cage and is made to hold the rotary axle for the beam ; the sides taper in a sweep- ing curve to the base. The construction should start with bolting two lengths of angle iron (which must be exactly the same length) together to form the corner pieces (four in all) and making the base of angle iron 5 -ft. square. The two 9 -in. squares of the same material for top and bottom of cage should also be assembled.

One of the cage squares should now be bolted to the tops of two corner pieces and the other 3 -ft. 1 -in. down ; this part remains square and the whole should then be laid flat on the ground, cage squares uppermost, and the bottom of the corner pieces splayed out and bolted to one side of the base, which will stand upright without support.

The distance , pieces should now be bolted at the correct points to shape the side up ; the writer used angle iron for the first one up from the base to add strength, the remainder being 1 -in. strip.

The cross bracing should then be done with 1 -in. strip bolted at the cross-overs ;

a length of strong twine tied from the centre of the base at A to the centre of B will enable the side to be squared up

(Those interested in a sound engineering job, within the capacity of the average constructor able to work in metal, will find this article useful. It will easily support a 10 - metre beam at a height of 30 ft.-Ed.)

correctly if the twine is brought into the centre of each spacing piece.

Constructional Details After this side is complete it should be

turned on edge and the second one made, when it will be found that the base will support it. Anti -rust paint should be run well into the joints and the surfaces that overlap each other should be given a coat before bolting together. One side has extra cross -pieces from 10 ft. up to act as a ladder and a small platform at a convenient working height enables one to stand easily. Two plates with 1 -in. drain holes should be bolted to top and bottom of the cage pieces to act as bearings for the axle, which consists of inch -pipe with a 9 -in. plate fixed to the top on which the aerial array can be bolted. This plate runs on an old ball race for ease of turning. A visit to a car scrap yard produced an "Austin 7" steering -box .with worm and pinion ; with a little care it was adapted to bolt to the bottom cage -plate, the steering column coming out horizontally. A pulley was fixed to this for a drive from the base, or if preferred the centre axle can be taken down the full length of the mast and a motor drive fitted at the base. As the axle is hollow the coax feeder can be run up the centre of the tube if desired.

Fixing down of the mast was accom- plished by four 18 -in. Lewis bolts in 9 -in. square concrete blocks 24 ins. deep at each corner, so that the bolts were just inside the angle at the corners.; g -in. plates were bolted corner -wise to hold each leg down.

Hoisting The mast call be raised either with the

help of a gin -pole or simply by pushing up with a ladder or pole while one helper pulls from behind and two others keep the whole thing steady with guy ropes until it is vertical. The construction is such that the top would have to sway at least 3 ft. before the centre of gravity came outside the base area, which obviously could not happen if the base is held down


in the manner described. A pulley is fixed to the top member so that a long-wire aerial can be hoisted if wanted.

Constructing a mast of this type has the advantage that one can build up on the ground, and if in a few years' time any

serious repairs are needed, it can always be let down again to effect these in comfort !

The writer's thanks are due to G8ML for very useful suggestions on the construction.

Cage

Platform

3'

9" sq.

3' I"

5'II"

9" sq.

l' 3" sg.

2' 2' sq.

é 3' sq.

4' sg.

5' sq. base

Ist side on ground side view

Top & bottom of cage

l

33'

Base

// u.n............u.......n.n

$ Lewis bolt

V

Plate to clamp down base

Corner fix rig

Lewis bolt

Ground level

Concrete

Corner bases

Ball race

Platform

N

Top plate for aerial

axle

Cage

Bottom plate

MORE ON

As if in confirmation of the various comments on this situation which we have printed recently, we have just received a copy of the "official" notice circulated to all DA's by their own under -cover organisation asking them to desist from further illegal operation.

This notice asks for "complete radio silence in Bizonia" since negotiations con- cerning the issue of licences have reached a decisive stage. There are good reasons to hope that German nationals will be freely

T}{E DA's

and officially licensed beginning about the middle of July, but it seems that for this to become possible, all DA operation must cease forthwith.

We also gather from this same notice that there has been a vigorous round -up of active DA's, the result of a "betrayal" to the authorities by one of their own number! The circular also makes it clear that S.A.C. (the German under -cover organisation) will accept no further responsibility in the negotiations for licences if DA operation is not immediately suspended.

240 SHORT 'WAVE MAGAZINE JUNE 1948

BCI From 1.7 and 3.5 me How Receiver IF's Affect the Case

By G. C. TURNER (G5IH), Cdr. , R.N.

IT is often reported that an amateur station is heard on the medium and long -

wave broadcast wavebands as a "tunable" signal and sometimes heterodyning a BBC station.

This type of interference can occur at some miles from the amateur station and on a frequency which appears to bear no relation to the transmitted frequency and/ or the intermediate frequency of the receiver concerned. It does, of course, depend on these frequencies or their har- monics, although their derivation is often difficult to visualise.

For clarity, in the simple formula given below :- -

ORM = the frequency on which unexpected reception occurs.

ORG = the frequency on which the amateur station is transmitting.

IF = the intermediate frequency in the receiver.

The first two cases are the obvious ones which need hardly be mentioned :--

(a) 'Where the transmitter is tuned to the second harmonic of the frequency on which it is received (interference usually weak and limited in range) :-

QRG = 2QRM (1)

(b) Where the transmitter is tuned to the second channel of the receiver :-

QRG =(QRM+ IF) +IF = QRM + 2IF (2)

Remembering that the expression (QRM + IF) is the frequency to which most oscillators are tuned, the next two combinations of frequency are the cause of most of the mystifying reception of l'7 and 3'5 me transmissions on the medium and long wave -bands.

If we consider the second harmonic of the oscillator in the broadcast receiver, 2(QRM + IF), when the transmitter is tuned the number of kc on the intermediate frequency either side of this frequency (assuming the receiver is a superhet of the comparatively unselective `aerial straight into the mixer stage" type) quite a strong signal can be tuned in on the

This is a very interesting analysis of how the receiver IF can produce tunable interference right on a BBC transmission, and he article also shows how to calculate the radiating frequenc'es to be avoided in particular

casts.-Ed.

broadcast bands. Thus :- QRG = 2(QRM) + IF) f IF -2 QRM +31F (3) or =2QRM+IF (4)

More mystifying still, the second harmonic of the amateur station can cause interference in the same way, i.e. :-

20120 2(QRM + IF) ± .TF'

QRG = ORM+32íF (5) or = QRM + 4 IF (6)

Taking the six formula above we can find the frequencies to be avoided in order to miss, say, the Home Service on 877 kc on a receiver using the normal IF of 465 kc :-

QRG = 2QRM (1) = 2 a 877 = 1754 kc

QRG = ORM + 2IF (2) = 877 + 930 = 1807 kc

The other formula for 877 kc do not fall in the amateur bands.

For the medium -wave Light Programme on 1149 kc, taking Formula 3 (the only formula that affects the 3'5 me band when an IF of 465 kc is being Considered) :-

QRG = 2QRM + 31F (3) + 2298 + 1395 = 3693 kc

And Formula 5 :

QRG = QRM + 0 IF (3) = 1149 + 697"5 = 1846"5 kc

As far as the amateur bands are concerned, the long -wave Light Programme on 200 kc is only affected by formula 3

ORG m 2QRM -4- 3IF (3) = 400 + 1395 = 1795 kc

Thus, in the Home Service area there are five spot frequencies in the amateur bands which can cause this type of interference. It is not suggested that these frequencies, and corresponding ones in other BBC areas, should be avoided (not forgetting that all receivers do not use 465 kc as intermediate frequency!). But the details given may be of some use in avoiding interference where it is known to exist, and where its intermittent nature, in the sense of different receivers at varying distances, has not previously been explained.


Going Portable Advice and Suggestions

By THE OLD CAMPAIGNER

A T this time of year when the call of /I the open air rivals the attractions of the shack, what could be more inviting than the prospect of using one's station (or part of it) out-of-doors and so carrying on the favourite hobby whilst enjoying whatever a British summer may have to offer? The bogey which often frightens off the likely starter is the problem of power supplies, but this can be surmounted and it is truly surprising to discover how much can be done with portable QRP equipment. The bogey is further dispelled by the prospect of being able to erect a -1-wave aerial for 1.7 me or a 5 -metre beam 1,000 ft. above sea -level, according to which happens to be one's favourite band.

Licences Most readers will be aware that the

G.P.O. is prepared for a modest supple- mentary fee of 10s. per annum to grant facilities for portable operation on all the amateur bands. The power limit is 25 watts input and the radius of operation is 10 miles from any fixed point chosen by the licensee. Stations licensed for portable work use the prefix /P when operating as portable stations.

Sites It should be realised that the holding of

a portable permit gives the operator no right to set up his station on private land and it is always a wise precaution to approach the landowner or farmer before committing a trespass. A few words of explanation and a statement of one's intentions will be well repaid and will usually result not only in willing permission but often in active help and welcome interest.

Portable or Mobile The prospective outdoor operator must

be systematic and painstaking. This is no pastime for the commercially -minded ham who "has no time" for designing or

(This pseudonym conceals the callsign of a well-known amateur who for many years has made the outdoor aspect of Amateur Radio operation his special interest. His article discusses portable operation from the strictly practical view point and is based on personal experiences. Ed.)

building his own gear. The privileges of working a portable station are generally reserved for those with an experimental turn of mind and a touch of ingenuity.

The first main question is of course the means of transport and one must decide between Portable station working or a truly Mobile station. The former may be regarded as a station which is assembled at and operated from a chosen site, whereas a mobile station is one which moves about as a whole, can be operated from any point and perhaps be "on the air" whilst actually moving.

Choice of the above will obviously depend on available transport. The design of mobile transmitters and "transceivers," sufficiently light to be carried whilst walking, demands real skill and in the writer's opinion is a branch of Amateur Radio which merits considerable attention. Short-wave listeners can get endless pleasure from a home -built midget receiver for the amateur bands which can literally be carried in the pocket, to be taken on holidays and elsewhere. This type of activity has become increasingly worth -

Running a portable outfit under open-air conditions is not as easy as it looks.


while since midget low -consumption valves and light -weight high-tension batteries have come on the market.

Crystal -controlled transmitters employing one or two valves only and operating with a plate -voltage of 100 or 120 volts have a surprising range when properly coupled to well -designed aerial systems.

Transmitters It is not proposed to give detailed advice

on the design of apparatus in these notes, but rather to leave this to individual choice which will largely depend on requirements. In any event, economy of power consumption must be the key -note in design and this means a minimum of valves and a careful selection of types. Three will usually be the limit for the transmitter, even if modulation is included. A simple 6F6 -6L6 or similar combination will serve on most bands and even a 6L6 crystal - oscillator alone is capable of giving excellent results on the lower -frequency bands. For 58 mc, a separate power - amplifier stage is to be preferred and this can be achieved if a tri-tet CO using a 7 mc crystal is followed by a double -triode such as the 6N7, each half of which acts as a frequency doubler. The DET19 makes a highly efficient PA on this band.

VFO's can of course be employed but frequency checking apparatus should then be available as even the best -made units are liable to suffer from the "ups and downs" of portable operation.

Receivers Questions of portability and power con-

sumption usually call for simplicity and compactness in receiving equipment for outdoor work and it is generally worthwhile to build special apparatus for the purpose. There are one or two important considerations to be borne in mind if this course is adopted. Additional rigidity and the protection of all vulnerable parts of the receiver must be secured, together with stout external connectors which will stand up to constant use.

If the receiver is to be used in the open air, the signals will often be heard through QRM from outside sources, such as con- versation, dogs barking, passing aircraft or traffic. Some reserve of LF amplification is therefore desirable to drown this kind of interference. Secondly, with the apparatus out of doors and often situated in windy locations, special precautions must be taken, particularly on the higher frequencies, to ensure that the receiver tuning is not affected by movements of the

aerial or its feeders. This generally demands the isolation, in a straight receiver, of the detector stage from the aerial by a stage of RF amplification. On 58 mc a second stage may be necessary to ensure absolute stability. If it is essential to use a receiver employing one or two valves only a partial cure may be secured by coupling the aerial feeders very loosely to the input stage-though some loss in input is of course inevitable with such an arrangement.

As with the transmitter, the final choice of design depends on the exact purpose of the operator, but the above points should be always borne in mind. It may be possible of course to use a superheterodyne receiver with the portable station, and provided sufficient power is available, this will probably produce the best results. A check-up on consumption and a careful comparison with the capacity of accumulators or other sources of supply should be made before setting out with a multi -valve receiver.

For the "foot -slogger" or cyclist, there is now a good range of -midget valves available which enables one to put together a 3- or 4 -valve receiver in a remarkably small space and to supply it adequately with a single flash -lamp cell for the filaments. A small layer -built HT battery will deliver the necessary plate voltage.

Aerials As mentioned earlier, the real pleasure

of outdoor work often lies in the opportunity of erecting the best types of aerials in the best kinds of location.

Perhaps the first problem to solve is the method of support. For the longer -wave bands, where long wires are needed at considerable heights, trees offer the natural solution. Tree -climbing is not necessarily involved-in fact, the practised hand can do even better with a large stone at the end of a string, to be whirled round in a vertical plane and released to fly over a high bough so that the stone descends on the far side of the tree. With the two ends of the string "in hand" it is an easy matter to pull a length of rope or cord over the bough to replace the string, and the aerial insulators may then be attached ready for hauling up the aerial itself. If two trees a good distance apart are used, the aerial may be positioned well clear of both of them. A very impressive half- or full -wave aerial is quickly erected in this way.

It is generally a good plan to stake down the feeder via a suitable insulator leaving


a free length for connection to the apparatus. This avoids any danger of the gear becoming "air- borne" should a wind arise. When operating from a vehicle, the feeder may be similarly secured to the coachwork.

For 5- or 10 -metre work rotary systems or rigid dipoles may be preferred, in which case the construction of a light duralumin mast on the fishing - rod principle may be undertaken. The mast is conveniently lashed to the car -bumpers or to a tree - stump or may be held vertically by guy -ropes. Various methods may be employed for rotating these aerials, but it will be a convenience if the rotation can be carried out by the operator whilst he is listening to incoming signals.

Power Supplies As there are many

possible sources of power for the portable station, it would seem logical to deal with these in order of size and capacity, commencing with the smallest.

At the start it must be realised that ' a station, if not employing a combined receiver and transmitter (i.e. a transceiver) needs low -voltage supplies for receiver and transmitter and high -voltage also for both.

The advisability of using throughout heaters or filaments of the same voltage will be obvious.

Simple receivers may employ midget valves with 1.5 -volt filaments. Such valves could be used in a very low -power transmitter-in which case all low -voltage requirements would be met by installing one or two dry cells.

Most apparatus, however, is likely to contain indirectly heated valves with 6.3 - volt heaters and these may be adequately supplied from car or motor -cycle accumulators. If the station is to be operated regularly from a car it is convenient to run a pair of leads from the car accumulator (or one half of it if 12 -volt) to a suitable plug screwed to the coachwork. Never -

The lighthouse supports the far end of a 1.7 me i -wave aerial (264 ft.). and the operators on this station worked in shifts.

theless, for prolonged use of the station, the operator will be well advised to carry a spare accumulator to guard against possible exhaustion of the car battery and consequent immobility of the car itself.

For medium-sized apparatus, 6 -volt motor -cycle accumulators provide satisfactory sources of heater supply, and can easily be carried by hand. A single M/C accumulator will supply a 3- or 4 -valve receiver reliably for a full day's operating, the total consumption being in the region of 1 to 1 z amps.

Turning to high voltages for plate supplies, the simplest source is obviously the dry high-tension battery. This will be quite adequate for all receivers except large multi -valve affairs and will also give reasonably long service to transmitters requiring an input of not more than one or two watts. As hinted above, this kind


of genuine QRP work provides one of the most fascinating forms of outdoor experiment and can give surprising results.

The more substantial forms of high - voltage equipment require motor transport and the power is generally derived initially from accumulators. A high-powered portable station will usually carry a petrol - motor or other equipment for charging the accumulators in turn.

Low -voltage DC current is converted to high -voltage DC in various ways. Vibrators and rotary -converters are most generally used by amateurs. In either case smoothing of the output by means of the usual combination of condensers and LF chokes is essential. Particular care in the design of the smoothing unit will be required if it is to be used in conjunction with receivers, modulators or variable - frequency oscillators.

Many types of vibrators are now available, some styled "self -rectifying" and giving a DC output, others requiring separate rectifiers. Voltages of 200 or 300 may readily be obtained by means of vibrators, though the smoothed DC current available should be carefully checked against the total power consumption of the transmitter or receiver to be used.

Rotary convertors have happily come on to the market in vast numbers in recent

months, and are noted for their absolute reliability, long life and wide range of outputs. For use with accumulators, the 6- or 12 -volt input types are most handy, but it is well to remember that a high wattage output, however desirable, will be a severe tax on standard batteries and may possibly harm them. The wise plan is to match thé input requirement of the convertor to the maximum safe output of the accumulator and to operate the transmitter at whatever power is thus made available.

Power Another important advantage of rotary

convertors is the possibility of "under - running" them. For example, a 12 volt - input machine, rated to give 800 volts output will usually work very satisfactorily from a 6 -volt accumulator, and give a good output at about 400 -volts. It might even rotate and give something over 100 volts from a 2 volt source !

Although capable of standing up to severe wear and tear, rotary convertors always respond to good treatment and careful adjustment of the brushes. An occasional check on the ratio of input to output wattage will indicate the working efficiency and show whether adjustments are needed.

G2ATK/P, with an all -6V6 Tx and a Type 26 converter into an R.103 receiver. Each unit is built in an I.F.F. case, utilising the original rotary transformer

supplied for this particular radar equipment.

Assembly Everyone knows the

story of the battle which was lost "all for the lack of a horseshoe nail." The moral of this legend might well be applied to portable radio-the missing crystal which ruined a field-day-the 'phones which someone should have remembered before the receiver was trans- ported to the country !

Two precautions carefully followed will prevent this kind of minor tragedy. Make a list of everything which will be needed on the day and check it over before leaving. Secondly, assemble the station temporarily at home and if possible test it "on the air," thus ensuring not only that everything is included but also that all the gear is in working order. In- cidentally, it is a good


plan to attach circuit diagrams to all pieces of home-made apparatus to assist rapid fault-finding should trouble arise. Always be prepared for minor breakages and disconnections by taking one or two small tools, spare lengths of wire, clips, connectors, etc. The handy loop and flash -lamp bulb will be useful for quick checking of the transmitter output at each stage.

Other pieces of apparatus to be taken, if transport arrangements permit, are a field - strength meter (especially if beam aerials are to be used), voltmeters for checking accumulators and plate voltages, a milliammeter and perhaps an absorption wavemeter.

Operation By far the best way of avoiding muddle

and confusion in operating the portable station is by designing some kind of operating panel either to fit into the car or to stand on the ground. In a tent it may

be possible to erect a trestle table to take the operating panel.

The design of this piece of gear will depend on the apparatus with which it is to be used but amongst the fitments there will usually be aerial terminals, aerial change -over switch, key, microphone jack, rheostats for power control, sockets for connection to the transmitter, receiver, accumulators, power unit, modulator and so on. The key, microphone socket and change -over switch should be conveniently placed ; there may be room on the panel for the log -book and it is a good idea to attach the pencil by a piece of string other- wise it is sure to get lost in the grass or in the bottom of the car when urgently needed.

Some readers of these notes may by this time have come to the conclusion that they are mainly superfluous, others may decide that there's more in "this portable business" than they thought ! The Old Campaigner's last remark is "Wait till you've tried it. Portable radio isn't quite as easy as you'd think ! But it's great fun !"

THE GATTI-HALLICRAFTERS EXPEDMON This American -sponsored expedition is

working through the British East African territories of Kenya, Uganda and Tan- ganyika on a scientific survey, the objectives being Mt. Kilimanjaro, the Ngoron- goro Crater, the Serengeti Plains and the Mountains of the Moon in Western Uganda.

Callsigns as follows have been allotted to the Expedition : Uganda, VQ5GHE ;

Tanganyika, VQ3HGE ; Kenya, VQ4EHG ; and VQ5HEG. At the end of April, the Expedition had reached Arusha, 150 miles west of Kilimanjaro. It is hoped to operate from the very tip of that 19,000 -ft. mountain, the highest in Africa, using VQ31-1GE, and a special QSL card has been produced for all QSO's made from Kilimanjaro.

Due to the seasonal closing of the 28 mc band, on which VQ3HGE has been operating, contact has been lost by the Expedition's base station W9CGC, Chicago, at the Hallicrafters headquarters. Operating schedules and frequencies are :

1400-1600 and 1700-2200 BST, channels available being 28050 and 14160 kc for CW working, with 28375 and 14380 kc for 'phone ; the Expedition operators are W6PBV and WOLHS.

The mobile equipment carried by the

Expedition consists of two Hallicrafters HT -4E transmitters and an HT -18 VFO unit, the receivers provided being S-38, SX-42 and SX-43. The aerial system is a prefabricated rhombic designed for 7, 14 and 28 mc, which can be set up or taken down in an hour.

In view of the prevailing conditions on 28 mc, V.Q3HGE will no doubt be showing up on the 14 mc frequencies by the time this appears.

DX OPERATING MANUAL

A new publication by the Short Wave Magazine, Ltd., and the first of its kind in tais country, the DX Operating Manual will appeal to all in any way interested in working or hearing DX. Of seven chapters, each complete in itself and dealing fully with one particular aspect of DX working, it makes a practical approach to the subject in a manner never previously attempted. Well printed on art paper, of 40 pp. with colour cover, the DX Operating Manual costs 2s. 6d. (2s. 8d. post free) and can be ordered direct from the Circulation Manager, . Short Wave Magazine, Ltd., 49 Victoria Street, London, S.W.I.


D XCOMMENTARY ON CALLS HEARD, WORKED & QSL'd

Greetings once more, after a rather duller month than usual. Yes, we know the DX is always there, but it has been a bit harder, hasn't it ? And no one would claim that 28 me had been wide open all the time, would they ? (Or would they ?)

It seems to us that summer conditions arrived rather early this year ; all of a sudden one was conscious that one had to get up rather early in the morning to find 14 me at its best, and one also realised how unpleasant continuous static can be in the evenings.

But these slight difficulties don't deter the DX fraternity in the slightest, and as usual we have some very interesting letters and claims in the mail -bag.

Hot -under -Collar Department We have always had the idea that some

of these spiv -types are not really so clever ;

lots of listening during the past month has confirmed it. In the course of testing several different aerial systems on 14 me by using them on the receiver, all sorts of interesting things have come to light. One evening in May we decided finally that if certain quite well-known operators were as well supplied with brains as they appear to be with watts, they would have the makings of quite sensible beings.

This particular evening we happened on KB6AD, working an ON4. KB6AD is the kind of call -sign that produces a violent reflex action and sends the right hand stretching out for the transmitter switch, but on this particular occasion it wouldn't have been much good for us, because the transmitter wasn't there ! So we listened. Every time that KB6 came over to the ON4 in the course of his QSO, two Italians, one OK and several G's called him frantically ;

every time the ON4 went back over, the same thing happened. When KB6AD finally signed off, he sent, very slowly and carefully "Closing down now until tmw ... SK SK."

Well, that really started things ; and for a solid six minutes after that, there were half a dozen or so stations calling KB6AD. One of them was still at it nearly 15 minutes later. Meanwhile some quite nice

By L. H. THOMAS, M.B.E. (G60B)

DX a few kilocycles away was passing unobserved.

Ah, well ! There's another one born every minute. But this sort of thing has been happening every day of the month, and it is gradually forcing your commen- tator to the opinion that competitive DX just isn't worth the trouble. After all, while the neurotic brigade are indulging in this sort of foolery one can have a really good QSO in perfect peace with a ZS or a VQ3, only a few degrees farther up the dial.

News from Overseas So let's go overseas and forget the

Brainless Wonders for a while. Some very interesting news to hand, too. First, ZC1CL came on the air on April 24 for the first time. He is Dan Lockyer, ex-LI2CL, ex-MD1D. Whether he will still be about, in view of the situation in the Middle East, we don't know. He worked 8Z and 17C during his first five days on the air.

VSICR (Singapore) has been on since April 14, with 20 watts on 14,020 kc-full QTH in panel. VS9ET and VS9GT have both returned from Ornan, although we have heard another VS9GT active during the past few days. VS9ET, now at Skegness, tells us that he was using a 6L6 driving an 807 to about 15 watts ; the aerial was a half -wave Windom about 12 ft. high. The actual location was by the side of the airfield at Sharjah. 'ET says he got rather fed up with the Cali- fornia Kilowatt gang, who used to form a queue, but were not too particular about their relative positions in the queue. All outstanding QSL's will be sent when 'ET can press the XYL into service with the secretarial work !

VS9GT, now at Hull, also says " Please have patience, chaps, and you'll get 'em." We have one of his cards and we never even worked him-so he has got some !

'GT says his chief troubles out there were the humidity (guy ropes snapped at night unless one loosened them) and the way sandstorms made their way inside the rig.


General view of G2VV, Hampton -on -Thames, Middlesex. Equipment on the left includes a modified Type A Mk.III Transceiver, a Hartley ECO driver for 3.5 and 7 mc, and a modified Type 27 Converter unit for the VHF's.

The QRN they caused was also rather trying. VS9GT now patiently awaits his G call, and will see what it's like to try to raise some rare DX !

Harold Owen of ZD4AM writes from Newcastle, Staffs, where he is enjoying some home leave. He has had a few personal QSO's round about Rugby, and hopes to be in London later on. He, after reading certain remarks last month, hands the G's a bouquet for operating, and says the worst spivs are the W's ; but he does agree that G notes seem to have deteriorated.

MT2E (Tripoli) confirms that Tripoli- tania and Cyrenaica are now officially two separate countries. He, too, writes from home, but is going out there again. His experiences in getting on the air are worth retailing ; he had to build his transmitter from all sorts of U/S bits and pieces of service gear, and his shack was a bath- room ! Having first got the receiver working nicely, he turned to the transmitter and describes the next part of his experience as "three months' soul-destroy- ing purgatory." But it eventually worked.

The "gen" from Tripoli is that amateurs are licensed for 25 watts on 7, 14 and 28 mc, and the. majority use 14 mc only. Active ones are MT2A, MT2C, MT2D,

MT2E,tMT2F (all civilians), and MD2B, MD2G (ex-T1NS), MD2H and MD2I (all Services), plus TRIP, an American type using 600-900 watts !

MD5AK (Canal Zone) is still going strong and comments on the freak conditions on 28 mc during April. The band had been folding up by 1900 GMT, but he suddenly found W's and VE's coming through right up to midnight and even later.

VS2CH (Kedah, Malaya) is ex-G2CQJ, and at the time of writing is rock-bound with only one frequency -14,316. He is in a fine location, but has no mains ; so he is using an HRO vibrapack and a 6L6 tritet with only 200 volts, and the DX lads will really have to listen for him. Later he hopes to acquire a generator and run 100 watts of 'phone.

VU2FL (Siliguri, Assam) is active on 14 and 28 mc and is particularly keen on contacting GM stations. He has a Vee- beam on the U.K.-QTH in panel.

Peter Lovelock, ex-G2AIS, comes up with a long letter from New York, where he is now living. While on the air here he worked 650 W's, and is now trying to revisit as many of his old QSO's as possible. The only gear he has of his own is an


ZONES WORKED LISTING

Station

Post-war 1948

Zones Countries Zones Countries

G8KP G2AJ G6QB G3DO G2WW G4CP G3AAE

SVIRX G2VD G3TK G2AVP GBIP GSMR G6PJ

MDSAK G4AR G3BI

G2AO G2EC GBKU

G6XX G3BDQ G2BXP

G8PL G2HPF G3DAH

G2BJY G3ACC GSHH

G3BNE

G2BBI

G3DCC

ZC1 CI. (since API.

24)

G3DO G3ZI

G8QX

G2BXP

G3DAH

G6CB

G2VJ

G2BBI

'Phone and CW 40 40 40 40 40 40 40

39 39 39 39 39 39 39

38 38 38

37 37 37

36 36 36

31 31 31

30 30 30

25

18

14

176 162 158 157 157 142 120

149 136 126 118 114 108 76

152 125 107

112 110 105

99 98 94

93 90 77

92 86 83

60

52

32

38 37 36 37 29 38 37

38 28 32 34 33 30 22

27 35

28

32

26 24 26

31 29 31

15 14

23

18

14

8 17 8

'Phone only 37 37

34

32

30

29

25

18

122 122

108

80

71

70

56

48

33 21

24

26

30

25

16

18

125 100 92

107 87

104 88

120 64 81 70 77 41 40

75 68

70

72

52 61 60

80 48 72

32 41.

51

52

32

17

87 42

58

59

66

37

24

48

S38 receiver beside the bed, but he has been offered lots of the proverbial American hospitality and has managed to work several of his old G friends.

ZC6WL writes from Kendal, West- morland to say he is now QRT in

Palestine and that all his contacts have been QSL'd ; if anyone is still short of his card, please get in touch via BCM/QSL, London, W.C.1.

An interesting letter from ON4WX (Brussels) points out that all three -letter ON's are pirates, and that the maximum power permitted the licensed stations is only 35 watts-not very much with which to fight the , bedlam from the W's, as he puts it ! ON4WX has now obtained his DXCC, and cards from C8YR and VQ8AE ; he says that ON4TA has his 40Z and will be the first Belgian to WAZ.

The 14 me DX The event of the month has been the

appearance of ZD9AA on Tristan da Cunha, which has caused at least as much excitement as VR6AA's appearance last year. Several of the gang have worked him, but the first G station to do so appears to have been GSVU (Nottingham). 'VU snagged ZD9AA for his fourth QSO and his first G-fine business.

G2PL (Wallington) weighs in with some caustic remarks about the behaviour of "overgrown schoolboys on 'phone" and suggests that some of them should be made to operate CW for a while-preferably those who actually boast about their complete lack of Morse knowledge. But all this is by the way-'PL says 99 per cent. of his time has been spent listening, and the other 1 per cent. working ZD9AA, VP1AA, WOOZW!KS6, UF6KAB and KAC, and RV2/FO8. The latter is another one that has occasioned some hectic chases lately (including some pretty bad behaviour, again).

Now we have to report a kind of deputation, headed by G2WW (Penzance) on the subject of C6YZ. 'WW states the case more fully than the others and says that he is not prepared to accept a blunt statement from CQ or ourselves that "all C6's are in Zone 24." As he rightly says, C6YZ is in Sian ; Sian, on the Magazine Zone Map, is in Zone 23 ; and that boundary was drawn from CQ's own map. So what ? We, too, have been sorely bothered by this one, and it is obvious that the discrepancy is between CQ's map and its own "list of contents" of the various Zones. The answer, even though highly unsatisfactory, is this : We will acknowledge C6YZ to be in Zone 23 ;

we are absolutely satisfied that he is. But if you send the card to CQ with an application for a WAZ Certificate you will surely have it returned. The same applies to C6ATE, also in Sian. So the gist of the matter is that you can score


40 Zones with us, but you- can't score "WAZ" with CQ ; not until you produce a card from a C8.

Incidentally, G2WW, in common with ourselves and many others, has received a card from UF6AA for a QSO which never happened ! 'WW only needs a UM8 to complete his round -up of USSR districts.

On the subject of Russians-an amusing exchange was heard by G3ATU (Sunder- land). A UA3 called a UB5 ; he received an immediate reply from a UM, who, in turn, was promptly called by a UA6. All we can think of is "Spivski." 'ATU also queries the C6YZ position, and wants to thank a WO in Missouri for wrecking his QSO with an HP station. Every time 'ATU called the HP, this WO carne back on the same frequency and told him his sigs were FB !

Piracy Again Two reports of pirates this month.

G2FRY (Nottingham) says that a DAI has adopted his call and says "QSL via G2FRY"-but he disowns it completely. G2PV (Leicester) is accused of using 'phone on 7, 14 and 28 mc, and tells us that although he is 52 years of age he still pounds the brass ; and he hopes that the GPO will find the culprit and lighten his purse of a few odd coppers !

G2FFO (Burnley) has worked MIB in San Marino and received a card direct- so he is genuine. QTH in panel. G2AO (Malvern) brings up the C6YZ query, and adds that he has worked KB6AD, who is on Canton Island. This island once used the prefix KC6 (we worked K6ETF/KC6 last year for nis first G contact and never got a card !) but now comes under the Phoenix group like Baker Island and is KB6.

G8PL (London, N.W.3), of indoor aerial fame, complains of being flooded with reception reports from USSR. 'PL has worked ZD1LQ and sends his QTH, and was also pleasantly surprised to have a QSO of sorts with KAIABZ, although the latter said the DX bar was still in operati on.

G5WC (London, S.E.19) has scored his century at last with his 40 watts of CW and 'phone. He would like to know more about KNIZA-we seem to have heard of this one before. G3DAH (Herne Bay) tells us that he was the G station who worked W6YIL while the latter used first 3 and then 0.25 watts. (See p. 198, May, "QRPP.") He held the W6 for. 40 minutes on the low power, recorded him and played him back !

G. E. Tompkins, ex -RAF and now of Hull, put Trucial Oman (Arabia) on the DX map by opening up VS9GT out there, using a modified T.1154 and an AR -88. Many excellent G contacts were obtained, and a total of 30C had been rolled in when VS9GT went QRT in

August of last year.

G8KP (Wakefield) sends an impressive list of DX, as befits the top -of -the -list man. His six new post-war countries were VP2, F (Corsica), UL7BS, CR4 and GD. 'KP says there are so many phoneys around that we should really run the Zones Worked list on confirmations only. He has 120, post-war-and we are delighted to cap that with our own 123 ! But what do other readers think ? Say the word-and if you want the list restricted to confirmed contacts we will be pleased to accept it.

G5FA (London, N.11) has added on another 7 Zones and 16 Countries this year. He collected WOOZW/KS6 without realising he was a new country (thought it was Swan Island !?. "Came the Dawn" while going home in the tube the following evening.

What is DX ?

Small prize to G3BQR (Christchurch) for the first really good answer we have ever seen to the question above. His answer is "Any country, until you have

C


DX QTH's

AP2G c/o Harbourmaster, Karachi, Pakistan.

AP2N Norman Henry, Police Training School, Karachi.

APSTM Capt. T. M. McLuskie, 160 The Mall, Lahore.

C6ATE Postal Bank, Sian, China. CR7MB Box 12, Quelimane, Portuguese East

Africa. EA8EDZ Apartado 11, Villa Cisneros, Rio de

Oro, Spanish West Africa. EQIRX Radio Workshops, Abadan, Iran. FF8FP Box 583, Dakar, French West Africa. HC20L Box 1293, Guayaquil, Ecuador. KAIABZ 520 Signal Base Depot, APO 707,

c/o PM, San Francisco. KM6AH c/o C.A.A., Midway Island, Central

Pacific.

M1B Geom. Mario Graziani, Repubblica di San Marino.

MT2E H. T. Orrell, Cables and Wireless Ltd., Box 400, Tripoli, Tripolitania.

RV2/F08 Roland d'Assignies, Isle de Raivavae, via Tahiti.

VP6SJ Box 252, Bridgetown, Barbados, B.W.I.

VS1CR Cpl. R. S. Baldwin, Signals Centre, RAF Changi, Singapore.

VS2CH J. C. Harvey (ex-G2CQ.O, Dublin Estate, Karangan, Kedah, Malaya.

VU2FL A. C. Watson, Gayaganga P.O., Siliguri, Assam, India.

WOOWZ/KS6 c/o Naval Station, Pago Pago, Samoa.

W3FOJ/KL7 Box 1310, Fairbanks, Alaska. W7MY 3211 Lambourne Avenue, Salt Lake

City, Utah. W4MCI/KG6 Amph. Trac. Co., 1st Marine

Brigade, e/o FPO, San Francisco. YVSAY Box 1247, Caracas, Venezuela. ZCICL F/0 D. E. C. Lockyer, Officers Mess,

RAF Amman, British Forces in Transjordan.

ZDILQ Lungi Airport, Freetown, Sierra Leone.

worked it and got your card." G4QK (Croydon) argues that we are revising our ideas of what constitutes DX, and says that in spite of the overcrowded conditions prevailing, it is easier to work VK, ZL and W6 than before the war. He adds that one can easily work 60 or 70 countries without including any real "DX" in the list.

G3TK (Leigh) has stopped calling it DX and says "not so usual" QSO's include VQ4KTH, ZD1LQ, YA3B, and LZ2AA. 'TK has to go off the air for a while to learn a new job, and hopes to find Zone 23 thickly populated on his return.

G6XY (Bigbury), who is ex-G8WL was among the lucky ones who worked RV2/

F08, and sends his full QTH, which appears in the list. G6BB (Streatham) has at last raised his missing VK6 on 14 mc, and sends some nice QTH's along.

G2HNC (Wirral) voices a mild protest against too many "rubber-stamp QSO's" -even with rare DX stations. He says, "It seems to me that when it becomes a matter of working DX stations to get an RST and a QSL and nothing else, it's a poor look -out for the future." We agree ;

it's a matter of keeping a sense of proportion. Chew the rag with the W's and the VK's and the ZS's-but don't hold up the KB6's and the ZD9's too long. They won't often encourage it, anyway. G2SO (Leigh -on -Sea) views the prospect in a different way and thinks that the competitive scramble will soon reach such a pitch that everyone will be trying to work 100 countries in a month, and again with each new transmitter that one builds. (But we argue, you don't have to do it if you don't like it ; watch the others collecting their nervous breakdowns and duodenal ulcers, but take it easy yourself !) 'SO worked VR6AB, who said his home QTH was the Swan Hotel, West Street, Horsham, Sussex, and that he would be returning shortly.

G2AVP (Stradishall) has been working some very good ones, such as KG6DI, TI8RB, CR6AI, KZ5BE, PK6XA, KM6AH, VP5MU, CO6AJ and W0OZW/KSó : all on 14 me CW.

Quick QSL Section Our remark last month about a rapid

QSL from LU has produced some amusing notes. G2BJY (West Bromwich) worked W6AY on April 24 and received his card on April 27 ! G2FFO (Burnley) worked a KG6 on- March 20 and had his card on the 27th. And he did a two-way QSL with a W2 in eight days last year. G4CP (Dudley) worked ZD3B on Friday and had his card by the Monday-but ZD3B flies for BOAC !

QRP G2AYQ (Bristol) raised CT2AG with

an input of 5 watts and habitually works on 7 mc with inputs of 3 to 5 watts only. His slogan is "More QRP, less QRM", and he wants a QRP Contest on . 7 mc during a week-end-phew ! G3DJD (Brighton) writes about his friend G3DIU/ A, who is a T.B. case and very poorly at present. He has spent the greater part of three years in hospital, learnt the code by listening on the amateur bands, and by the generous co-operation of the GPO passed the Morse test in bed. G3DIU/A


is now working on 7 mc with 8 watts, and a 9 ft. 6 in. rod aerial, with the bed as a counterpoise. He is CC on 7028 kc, and works between 0930-1115 and 1415-1530 when he is fit enough. So please look out for G3DIU/A and try to keep the channel clear for him if you can ; if anyone ever appreciated Amateur Radio as a hobby, a chap in these circumstances will. And hats off to him for his perseverance !

G3CWW (London, N.W.4) claims to have heard a UM8-normally the one district missing from the USSR scores. UM8KAB, he says, was about T3, starting at one end of the band and finishing at the other. .'CWW suggests that some of the grousers about rotten notes should listen to their own oc- casionally (we are not sure whether we like the sound of that one !) And he thinks his call is being pirated-on the strength of having received cards for contacts never made.

G6WX (Coventry) has received his DXCC Certificate for 100 countries on 'Phone. He must be the only Mayor in this country with a DXCC !

G3CVG (Wakefield), who was com- plaining about the absence of Russian cards, has now received about 40 ! He spoke too soon. He protests about the growing habit of certain G's-passing the "rare DX along from one to the other. Very pally, as he says, but it shuts out the rest of the gang and is forcing him to abandon his rock and build a VFO.

G3DBF (Mansfield) would like the QTH of LF2O. We know he's a Nor- wegian, of course, but take it he means

Jinin' Old Timers' Club, Jarge

the full QTH. Can anyone oblige ?

G8ML (Cheltenham) passes on a message from PAQ MM to the effect that VP6SJ is active most nights on 7060 kc. His QTH appears on the list.

David Mit:hell (ex-GW6AA, ex-G2II) dopes to be collecting a ZII call before very long. He is taking his own gear with him to New Zealand and will be looking out for all the G QSO's he can muster.

Stop Press G3CHN writes from the SS Francine

Clore, at Port Arthur, Texas, and expects to be on the Texas run (in a tanker) for some time. On the ship is a very fine transmitter running 450 watts to a pair of 813's-VFO controlled and would cover 3.5, 7 and 14 mc.... He would like the sea -going amateurs to organise themselves and plead with the GPO for a Maritime Mobile permit. But, as we see it, they are not under GPO jurisdiction when on the high seas ; it is surely up to the master of the ship and, through him, the Board of Trade. This is, however, not a matter on which we are 'qualified to advise and we do not want to be held responsible for encouraging what might be illegal operation !

Next month's deadline is June 17, first post. We would like to have your Zone and Country claims, in the order shown in this month's column, on a post -card, and separate from your letters. And if you would please divide your letters into paragraphs headed " 14 mc," " 7 mc," " DX QTH's," and so on, it would ensure that nothing is overlooked. As it is, we read about sixty letters for this feature and have to try to remember them all in case three or four people refer to the same thing.

Address all your news to " DX Com- mentary," Short Wave Magazine, 49 Victoria Street, London, S.W.1, and watch that date ! 73 until then-and may you always get T9x.

THE NEW CALL BOOK

The Spring 1948 issue is another monster production, and testifies to the rapid growth of Amateur Radio activity all over the world.

The G listings, in 34 columns, comprise about 4,000 addresses, and give the G calls printed in "New QTH's" up to and including our issue of March, 1948. But the G figure is still about two-thirds only of the total of amateur licences now in issue in the U.K.


Field

ylVmStreng

Field

Strengt y/Vrn

Field

Streng

µ/V,n

Twenty -Metre DX Forecast Predictions for June

S

® h

AFRICA Jun

& ASIA 10

º 00 02 04 06 08 10 12 14 16 18 20 22 00

TIM0 GMT

® AUSTRALASIA

Jun

1 O 00 02 04 06 08 10 12 14 16 18 20

TIME GMT

22 00

20

..i,

Is NORTH &

Jun SOUTH AMERICA

IO

..,,,,, \ mew.

n . 1

amen ..............,e, 09 10 i> 00 02 04 06

TIME GMT

by I. D. McDERMID, A.R.T.0 (GM3ANV)

HE maximum field strengths and periods

of activity for nearly all vu areas have by this month VQ4 reached their lowest ebb

in the yearly cycle. Further, it will be seen

ZSI that the slopes of many of the curves-such as VQ4, VU and ZS1- between 1200 and 2200 GMT show slower rates

vsi of recovery to their peak strengths than last month, and incidentally slower than for next month. VK2 has contracted quite appreciably and lost the morning period double - hump that was evident in May. There is little comment to be made with regard to the remainder of the graphs, since although they all give decreased peak intensity and periods of activity, the shapes of the individual curves have not

ZL altered substantially.

It might be of interest to note that the noisy land

6 areas due to local static have by now shifted and will remain virtually un- altered in the following positions until September: In Africa, the main belt of high noise source stretches between the latitudes 05 deg. N and 15 deg. N and includes the Southern tip of Arabia ;

in America, the noisy area embraces the whole of Central U.S.A. and the Eastern seaboards of North and South America from latitudes 05 deg. S to 35 deg. N, including the West Indies ; in Asia, the noise covers an area

L7 bounded by approximate - E7 ly 80 deg. E to 130 deg. E

6 by 25 deg. N to 05 deg.S. The above should be compared with the areas given in the April issue.


Simple Break -In System Circuit for BK

Devised by R. J. DONALD (G3DJD)

BREAK-IN operation does not seem to be used by amateurs nearly as much

as it deserves to be, and in this article it is proposed to describe a system which is comparatively simple and can be adapted to any superhet receiver.

The essentials are :-- (1) An oscillator than can be keyed. (2) A separate receiving aerial. (3) A key with back contacts. If the erection of a really efficient

receiving aerial is not possible, it is suggested that the best be made of a bad job and an aerial of some sort be put up (even though it be only a bit of wire across the room) on the argument that it is better to be able to work BK on some contacts that not to be able to work BK at all. When working weak signals the scheme can be dropped for the time and the main aerial used.

Basically the idea is to use the back contacts of the key to mute the receiver. Any method could be used, such as breaking the HT line to the Rx, but at G3DJD a very small "mod" was made to the station superhet, as follows :

The earthy end of the cathode resistors in the RF and FC valves were disconnected from the chassis and connected together and to one side of a closed- circuit jack socket. The other side was connected to earth so that with the plug out the circuit remains unchanged. How- ever, when a plug connected to the back contacts of the key is inserted and the key depressed the receiver is muted an instant before the Tx begins to radiate and the muting is removed an instant after the Tx stops radiating. It was further found that by connecting a resistor across the jack connections the Tx signal could be heard when the key was pressed-the size of the resistor being governed by the sensitivity of the Rx and the power of the transmitter ; 50,000 ohms is a good value to start with. If desired, and panel space permits, the resistor could take the form of a 5,000 or 10;000 fixed resistor and a 100,000 ohms variable resistor in series so

These notes will suggest the means by which BK operation can be achieved by the average amateur. Break-in working should be possible at all stations fully equipped for CW operation. When conditions allow,

it is a most satisfying method of working.-Ed.

giving control of the signal strength on "listening through."

Break-in means that in effect you can "listen through" when transmitting and it is therefore possible for the operator with whom you are in contact to let you know if he misses part of your message because of QRM or other interference. To stop you keying he should send either your call sign or better still a series of double dots .. .. . .

Operation With the modification described the

procedure is as follows :-Listen round for someone calling CQ, tune to his zero beat, switch off PA HT, swing VFO with the key down until the signal is heard in the muted receiver, check the VFO against the nearest crystal check point (see Short Wave Magazine, April 1948) tune the VFO to a suitable point 2 or 3 kc off the calling station's signal, let the key come up, switch on PA HT and as soon as invited to do so transmit. If working BKS the same applies except that the VFO is tuned to zero beat instead of to one side .... and the whole operation can be performed in a matter of seconds, though it takes so much space to describe.

Muting circuit applicable to any multi -stage receiver. The back contacts of the key are connected across the

jack.

Table of Values Fig. 1. Receiver muting circuit

vl V2 Rl, R2 = Cl, C2 = R3 J=

RF valve FC valve Existing bias resistors Existing bias condensers See text-about 50,000 ohms Closed circuit tack connected to back contacts of Key

Note : In the case of keys with a common moving contact-Le. metal arms-care must be taken to see that short circuiting does not occur.

C


THE VHF BANDS By E. J. Williams, B.Sc. (G2XC)

AACTIVITY on 58 mc has been at a consistently higher level during the

past few weeks than has ever before been experienced. It has been a pleasure night after night to swing round the dial and hear so many signals on the band. What- ever the cause may be, it is much to be hoped that this activity is going to continue for as long as we have the use of these frequencies.

No new distance records are reported, although some new trails have been blazed. Starting with the GM3OL/G5GX contact, mentioned last month, GM3OL effected QSO with several Lancashire, Yorkshire and North Midlands stations and has been heard in Birmingham by G5JU and also in Rugby. G3BW (Whitehaven, Cumberland) has been doing similar excellent work and records reception of G5BM (Cheltenham) and G5PP (Coventry), for really good long - haul paths. And just as we started this, the Newcastle group broke through to Hull, G2BS and G3CYY working G3ALD (Hull) on May 14. On the same evening, G6OS of that city worked G2BS and G5GI in Sunderland, and G3CYY and G4LX (Newcastle). So the North is pretty active.

All these contacts are the reward of much hard trying and we congratulate the operators concerned.

With such excitement in the North southerners have had their thrills in the way of new counties. G3KX/A and G4RX appeared in Somerset, G2RY and G3TN in Dorset and G5AM in Suffolk. For those not already having included Worcestershire in their list, G2HX re- appeared, during M.A.W.E. No. 3, after a year's absence from the band. In the Channel Islands GC4LI is listening and has logged G5BY and G3AVF.

Band Planning As will be gathered from the foregoing,

conditions have been generally good. M.A.W.E. No. 3, like its predecessors, was blessed (or cursed, whichever way you look at it !) with fine weather, but this time both conditions were good and activity high. So exceptional was the latter that the LF end of the band became

First Spor-E Working- Excellent GDX Conditions-

Increasing Activity- VHF Century Club Founded-

one mass of QRM on the Sunday evening !

One South London station left his receiver set on a frequency near the LF end for 30 minutes and during that period 14 different stations appeared on that one spot! Several well-known stations shifted up towards the HF end and we have been asked to appeal to all concerned to spread out more evenly over the band. In supporting this appeal, we must ask your forgiveness if G2XC continues to operate on 58'67 mc. Truth is, that if we go much higher up we are liable to cause harmonic interference to a local airfield, and this same restriction applies to several stations in the South Hampshire area.

However, when we get going on 144 mc G2XC will be in the HF half even if it does mean no QSO's ! Or will some of you come and keep us company ? If so, order a crystal between 8055 and 8111 kc !

G2XC will be on 18 x 8070 kc, and G6VX on 145 mc.

But returning to the present band, all operators are urged to use the QLM, QHL, QMH, QML procedure signals to indicate the direction Of search after a

M.A.W.E. No. 4

The next Magazine Acti,ity Week -End is June 12-13, starting at 1500 BST on the Saturday. Please report results

to reach us by June 18.

CQ. Further, if all stations (particularly, those outside the London and Home Counties area) would tune the band alternately from the HF and LF ends, it would encourage a migration towards the HF end. At present, any London station who moves above 59 mc is a hero !

And while on the subject of operating, may we remind those pestilential VFO swoopers that the spiv tactics they see fit to employ on the LF bands are NOT wanted on the VHF's. Complaints are beginning to come in about this, complete with the offenders' call signs. We don't want to start a black list, but suggest that GDX stations refuse to QSO operators seeking contacts by intentionally parking on top of a successful station.


Sporadic -E The only spor-E contact on "five"

reported so far is G6ZQ (Cheltenham) with OK2MV, on May 5 at 1305, although G6DH (Clacton) worked W1PPH/MM 28/50 cross -band on May 10, when the W1 was near Gibraltar. That same evening some queer signals were heard around 58'5. Fading was severe and identification impossible, but it was almost certainly due to spor-E. G2ADZ logged OK3BV/3 for a few minutes around 1430 BST on May 16.

EP3H is active in Persia, beamed on G with 20 watts (CW only). Another station is on in Dhahran, Saudi Arabia, on 60 mc, Reports can be sent via BCM/QSL. London. From his letter we gather EP3H may be on 56 mc, i.e. outside our band.

Swiss Note HB9BZ writes that the HB's are lined

up for when the spor-E season gets going. HB9AT and HB9BZ have been carrying out some interesting propagation tests. With 100 km. separating them, the circuit is generally very poor with fading when beams are lined on the direct path, but if both stations aim their beams at the famous Jungfrau -Massiv the field strengths increase by 8 dB above the maximum on the direct path, and fading is eliminated. These tests have been repeated at different times of the day and over several weeks.

HB9BZ is active at 1200 and 1700 GMT daily and hopes to QSO G's before long.

Individual Reports Thanks to G5BM (Cheltenham),

amongst others, for encouraging G4RX (Bridgwater) on to the band and so enabling us to add Somerset to the Counties list. Outfit at G4RX is a 25 -watt 807 power doubler on 58'6 mc, a fixed dipole firing NE/SW, and a BC -342 with a Type 27 convertor. His best DX so far is G5GX and G6OS-and very good, too. The other Somerset station, G3KX/A, is installed at the QTH of SWL Bodeo- Yanez (Banwell). The input is 20 watts to an RK34, used as two separate doublers, following a KT66 tritet. The Rx is the same as at G4RX, but a 3 - element w.s. rotary 16 -ft. high is in use.

G2BMZ (Torquay) has been busy experimenting with a new convertor, which he hopes may be effective on 144 mc later on. It has a series -tuned parallel- bar circuit with two EF54's in push-pull. Coupling between the EF54's and the

616 frequency changer is by self -resonant coils (9 turns 18 -in. diameter). The 6J6 has grids in push-pull and plates in parallel. Another 6J6 is used as oscillator link coupled via coax to the frequency changer.

G3AVF (Torquay) reports for the first time ; he is on 58'98 mc, rather badly screened east and north, but is doing well with 22 watts to an RK34 push -push doubler, into a 4 -element w.s.r.b, with a Type 27/R.107 combination on the Rx side. He is another of those who observed the brief spor-E opening at 1800-1830 BST on May 10.

The North From the south-west to the north,

where GM3OL (Dumfries) and GM3BDA (Airdrie) have both been active. The latter, situated midway between Glasgow and Edinburgh, is 500 -ft. a.s.l. So far we have no reports of any G's other than G3BW contacting him, but GM3OL has been doing some fine work, up to 200 miles. He has been looking for G6VX at 2230 each evening. May 7 was a good night, and a determined effort was made to get through,, but G5MQ and G3ARS,

VHF CENTURY CLUB The following members of the

Five Band Club have shown 100 QSL cards confirming two-way contacts on frequencies above 50 mc, and thus become Founder Members of the VHF Century Club :

G5PY G2AJ G6VX G2MR G5BY

G5BD

G2XC

R. Clark (Clapham Park) R. Joss (Hendon, London) M. D. Mason (Hayes, Kent) W. J. Thompson (Surbiton) H. O'Heffernan (Thurle-

stone, S. Devon) A. C. Simmons (Mable-

thorpe) E. J. Williams (Portsmouth)

ASSOCIATE MEMBERS Following is a list of those who, having shown

totals of over 100 stations worked, are granted associate membership pending receipt of the necessary QSL cards :

GSRP G5LQ G3BLP G6OS G4Ro G2RI

E. Wake (Abingdon) J. Tovell (Chiswick) J. Haydon (Selsdon) J. W. Gill (Hull) A. E. Read (Welwyn)

L. Ridgway (Leicester)


both in Lancashire, were the best contacts achieved.

South of the border G3BW (White - haven) has provided a new county for some of the Northern and Midland stations. He is working G3APY (Kirkby) regularly. The Tx at G3BW is a Type 37 driving an 832 PA on 58'9 mc, into a 3 -element rotary (a 4 -element is under way). The Rx is an EF54-EF50-EC52 convertor into an SX16. Operating hours are from 2130 nightly and all day on Sundays. Sunday, May 9, when G3APY, G3DA, G6MZ, G5TH, G6LC and G3BY were worked and G5B M heard was the best day of the month in Cumberland.

On the north-east coast a large group is active in the Newcastle area, from 2130 to 2300 BST nightly. The cälls include G2BDQ, G2BS, G2CO, G3ACK, G3CYY, G4LX, G5GI and G5KL.

FIVE -METRE COUNTIES WORKED LIST

Starting Figure, 14 From Fixed QTH only

Worked Stations

31

30

29

28

27

26

25

23

22

21

20

19

18

17

16

15

14

G3BXE (126), G5BD (147), G6XM (211) G51.4Y

G2MR, G2NH (251), G5MA, G6OS (124), G6VX

G2ADZ (102), G201 (106), G2XC (257), G3BLP (163), G5BM, G5RP (124), G8UZ

G2CIW (139), G5MQ, G6LK (225)

02A3 (191), G4LU, G5PY (207)

G2RI (102), G3ABA, G3IS (102, G6MN/A

G5GX (110), G5JU, G8SM G3MY, G3PZ, G4IG (163),

G60H (129)

G2ATK, GSIG, G6YU G2A0K/A, G4AP, G4RO (110),

G6KB (109), GIKZ G2BMZ, G2YL, G5PP, GSAL

G2NM, G6HD G3BK, G5LQ (141)

G2KF, G3WW, G6CW, G6LX, G8QM/A

G3AAK, G3DCV G4AJ, G3BOB, G6VD

G2AUA, G2HDY, G5BJ, GSHN, G5MR, G6UW

Note: Figures in brackets after call are total of different stations worked : starting figure 100.

G2BS (Sunderland) is using an acorn superhet, while the Tx is all EF50, the final being two in push-pull with 7 watts input. A 3 -element beam 12 feet high will be raised to 30 feet as soon as the mast is obtained. G2BS is on " five " only and we are glad to know that he has got through to Hull after but 3 weeks on the band.

The past month has been one of great achievement in the Hull area, to judge by the almost daily arrival of letters and even telegrams reporting new results. Not a little of this enthusiasm is due to G5GX and we are very glad to welcome him to the Fiveband Club this time. During the past month G5GX has worked 26 different stations and heard 20 more. His most consistent DX signals are GM3OL (whom he can hear whenever he comes on), G4RX, G5RP and G6XM. G5GX receives G3BW well but the Hu11 stations are not audible in Whitehaven. By May 17 G6OS had worked Newcastle for four nights in succession.

Midlands G5PP (Coventry) has a single dipole

42 feet high radiating NW and SE, and fed from a 5 -stage Tx ending in a DET 12. The Rx side is a Type 26 convertor into an HRO. He has been putting a very consistent signal down to the south coast. and has started to climb up the counties table. G3ABA, still looking for Sussex and Devon, found M.A.W.E. 3 good, and comments on the number of stations still on the air at 0115 on the Sunday morning !

In Northants G2AUA (Wellingborough) hopes to have a 4 -element beam up shortly, while G3BBA (Towcester) is a welcome newcomer. We wish we had space to give all the very interesting detail on his equipment which G3BBA has sent.

In brief, his Rx is a double superhet (3'2 mc and 465 kc) with EC52 (GGT) and EF54 RF's, EF50 mixer and 6J5 oscillator. Variable IF bandwidtns are available, while the noise limiter follows the audio waveform. This Rx is also capable of receiving FM. The Tx starts with a VFO on '875 mc and finishes with an RK34 strapped and cathode driven from an 807. FM with an available deviation of 20 kc is in use. A 4 -element rotary will soon be in position to replace the 40 ft. high dipole used so far. G3BBA is also ready for 144 and 420 mc and promises details in due course. Prepara- tions for 2300 mc are under way, too -he


Tx for 144 me designed and built by G6VX, Hayes, Kent. The driver uses Mullard EL91 miniature valves, and the fina is an 829. We shall be publishing full details of this very fine transmitter as a constructional article in an early issue.

is to be congratulated on his initiative and enterprise.

In Nottingham, G3DG started activity on " five " during M.A.W.E. No. 3 with a 6J6 mixer-osc. into an AR88. His Tx is 4 -stage finishing with an 809 PD. A 3 -element c.s. beam should be up by the time this is in print. In Rugby, G3IS has been joined by G8VN, who reports that G6YU has returned to 58 me after a long absence. Since April 20 G8VN has had a two -element beam in operation and 25 watts to an 807 PA. He would appreciate reports on his signals subsequent to that date.

Following on G2AJ/P's portable effort in Bedfordshire, G3CGQ (Luton) has commenced operations from a fixed QTH. He has a Type 27 convertor into

a 1-V-1 Rx, which answers some of those people who say a communications receiver is the only alternative to a super- regen on five. With it he has worked G3WW at 50 miles ! His aerial is seven half -waves long and fed 4a from one end by low impedance line. The Tx has an 832 PA.

Not far away, G5UM (Knebworth) continues active, when not preoccupied with things other than Amateur Radio. He still uses the line-up he described in the Short Wave Magazine for November 1946. One more county will see him in the Counties Worked panel.

South G2KI (Walton -on -Thames) recently in-

stalled a 3 -element beam 0.2À spacing,


FIVE -METRE CALLS HEARD G5GX, 30-32 Princes Avenue, Hull,

Yorks. Worked: G2ACZ, 2ADR, 2ADZ, 2AJ, 2RI, 2XC, 3ALD, 3APY, 3BK, 3BLP, 3BUR/A, 3WW, 4RX, 5BM, 5GS, 5MA, 5RP, SRS, 5WP, 5YV, 6BX, 6TF, 6VD, 6XM, 8VN, GM3OL. Heard: G2BMC, 2FKZ, 2FZR, 2HX, 2MV, 2NH, 3AEX, 3BOB, 3AUS, 3BW, 40F, 5PP, 5RP, SUS, 6DH, 6MN, 8AL, 8UZ, 8WV, GM3BDA.

G5BM, Berriville, Arle Drive, Cheltenham, Glos.

Worked: G2ADZ, 2XC, 3BY, 3KX/A, 3YH, 4R0, 4RX, 5BD, SBK, 5L0, 5RP, 5YV, 6ZQ, 8WV. Heard: G2BMZ, 5MA, 5PP, 5WP, 60S, 6VX, 8UZ. (May 1-14.)

G201, 25 Boothfield, Winton, Eccles, Lancs.

Worked: G2NH, 3BW, 3DA, 4RX, 5PP, 5MA, 5US, 6XM, 6LC, 6SQ, BUR. Heard : G2AJ, 2MR, 2ADZ, 2XC, 2ALN, 2MV, 2FKZ, 3DG, 3ZK, 3DH, 3APY, 40S, 5MQ, 5BM, SHN, 5RP, 5GX, 5BD, 6VX, 60S, 6TL, 6QT, 6PD, 6SN, 8VN, 8AL. (May 7-9, M.A.W.E. No. 3.)

G6KB, Stoke Row, Henley-on- Thames.

Worked : G2BMZ, 2AOK/A, 2XC, 2YL, 4KD, 4R0, 5L0, 5LQ, 613P, 8AL, 8TH. Heard: G2FWD, 2MV, 2NH, 3BLP, 3WW, 5HN, 5NF, 5RP. SUS, 6HC, 60H, 6UH, 8KZ, BWC, (May 9-M.A.W.E. No. 3.)

G3IS, 59 Eastlands Road, Rugby, Warks.

Heard or Worked : G2ADZ, 2AJ, 2AOK/A, 2FKZ, 2MR, 2MV, 2NH, 20I, 2RI, 2XC, 3ABA, 3APY, 3BBA, 3BJQ/A, 3BUR/A, 3BLP, 3BYI, 3DA, 3DCV, 3DG, 3WW, 3ZK, 4LU, 4RX, 5BD, 5GX, 5JU, 5MA, 5MQ, SMX, 5PP, 5RD, 5RP, SUH, 5WP, 5YV, 6GR, 6MN/A, 60S, 6SN, 6VD, 6VX, 6XM, 6YU, SAL, SUZ, 8VN, 8WV. (April 15 - May 12.)

G5BD, The Elms, Church Road, Mablethorpe, Lincs.

G2ADR, 2AJ, 2AUA, 2CIW, 2FKZ, 2HDY, 2MR, 2MV, 2NH, 20I, 2RI, 2XC, 2XV, 3AEX, 3ALD, 3BK, 3BUR/A, 3COJ, 3DA, 3DCV, 3IS, 3WW, 4LU, 40F, 5GS, 5GX,

5KH, 5MA, 5MQ, 5PP, SRP, 5RS, 5PY, 5YV, 6DH, 6HC, 6LC, 60S, 6XM, 8AL, 8DV, 8KZ, 8SJ, 8UZ, 8WV. (April 15 -May 10.)

G3AVF, 3 Clarendon Park, Tor Vale, Torquay, S. Devon.

Worked: G2NH, 4RX, 5MA, 8AL. Heard: G2AJ, 2FKZ, 3AAT, 3BLP, 3TN, 5RP, SUS, 5WP, 6KB, 6VX, 6XM. (May 1-13.)

G3BLP, 52 Littleheath Road, Selsdon, Surrey.

Heard or Worked : G2ADZ, 2AK, 2BMZ, 2HX, 2PT, 2QY, 3ABA, 3AEX, 3AEZ, 3AUS, 3BBA, 3BHJ/A, 3BK, 3BUR/A, 3FP, 3KX/A, 3WW, 4LU, 4RX, 40S, 5GX, 520, 8KL, BTL. (April 18 -May 14.)

G2NH, 75 Woodlands .Avenue, New Malden, Surrey.

Worked: G2AUA, 2BMZ, 20I, 2XV, 3ABA, 3BBA, 3BK, 3WW, 5BD, 530, 5PP, 60S. Heard: G2ADZ, 2XC, 3AUS, 3AVF, 3DG, 3IS. 3ZK, 5BY, 5GX, 5L0, 6MN/A, 8KL, 8TH, 8VN, FBNW. (All over 50 miles. M.A.W.E. No. 3.)

G5MR, South Lawn, Admiralty Road, Felpham, Bognor Regis, Sussex.

Worked : G2ADZ, 2MV, 2XC, 4R0, 5PY, 6NA, 8LO, 8R0. Heard: G2FZR, 2HLF, 2NM, 2YL, 3AUS, 3CWW, 5HN, 5MA, 5RP, 5WP, SUS, 6KB, 6XM, 8DV, 8WV. (All during M.A. A.W.E. No. 3.)

G5LQ, 12 Cambridge Road. Chis- wick, W.4.

Worked: G2XC, 3ABA, 4GB, 4IG, 4R0, 5L0, 5PP, 6NA, 6KB. 6PA. Heard : G2ADZ, 2HX, 2I(1, 2MV, 2PT, 2RX, 2YL, 2ZV, 3BLP, 3BOB, 3NR, 4CG, 5BM, SUN, 5KH, SKJ, SUM, 5VB, 5WP, 6HC, 6HD, 6NK, 6UH, 6XM, 8AL, 80V, 8TH, 8WV. (M.A.W.E. No. 3.)

G8VN, 7 Lawrence Road, Eastlands, Rugby °,

Heard : G2ADZ, 2A3, 2AK, 2AOK/A, 2MV, 2MR, 2NH, 20I, 2XC, 3APY, 3BBA, 3BLP, 3BUR/A, 40A, 4RX, 5BD, 5BM, 5JU, 5MA, 5MQ, 5PP, 5RP, SUR, 60S, 6SN, 6VX, 8AL.

and now hears even G2XC's 'phone !

G5RP (Abingdon) has tried eight different convertors since January 1947 --seven of them home -built and three are still in use. These are (a) Type 26 into HRO (b) 6AK5-955-955 into HRO-and (c) The

Worked : G2RI, 3ABA, 3IS, 4LU, 5GX, 5US. 5YV, 6VD, 6XM, 6YU, 8UZ, 8WV. (May 1-10.)

G2AUA, 29 Hill Street, Welling- borough, Northants.

Heard or Worked: F8ZF, G2FKZ, 2MV, 2NH, 3BBA, 3BK, 3BOB, 3CGQ, 3WW, 4IG, 4R0, 5BD, 570, 5L0, 5MA, 5PP, 5RP, SUS, 5WP, 6HD, 60H, 6XM, 8AL, 8KZ, 8WV. (M.A.W.E. No. 3.)

G8WV, 3 Church End. Hanslope, Nr. Bletchley, Bucks.

Worked: G2AJ, 2AUA, 2CPT, 2N11, 2XC, 3AEX, 3ALD, 3BBA, 3BOB, 3BUR/A, 4TG, 4R0, 4RX, 5BD, 5BM, 5PP, 5RS, 6HD, 6PG, SAL, 8VN. Heard : FBNW, G20I, 3AAT/A, 5WP, 5YV, 6HC, 60S. (Ma.'v 1-10).

G3WW, North House, Wimblington, Cambs.

Heard: G2XC, 3AAT, 3AEX, 3BLP, 3BUR/A, 5XD, 6HP, 6KB. Worked : G2AUA, 2FKZ, 2APP, 2MR, 2MV, 2NH, 2PU, 2XV, 3BK, 3BLP, 3DCV, 4IG, 4KD, 4R0, 5BD, 5GX, 5IG, 5J0, 5MA, 5PP, 5RP, 5WP, 60S, 6VX, 6XM, 8AL, 8KZ, BSK.

G5HN, 1 Conisboro' Way, Caver - sham, Reading, Berks.

Heard: G2ADZ, 2AUA, 2MR, 2NM, 2YL, 3A.AT/A, 3ABA, 3BUR/A, 3WS, 4IG, 5GX, SIO, .5MR, 5NF, ,5PP, 5WP, 6HC, 6NA, 6VX, 6XM, 8AL, 8PA. Worked : G2FKZ, 2HLF, 2HX, 2KI, 2MV, 2XC, 4R0, 5BD, 530, SKJ, 5L0, 5RP, 5RS, SUS, 5VB. 6HD, 6KB, 6UH, 8TH. (May 7-10.)

G3DG, 5 Alpert Avenue, Carlton Road, Nottingham.

Heard : G2ADR, 2A3, 2CPT' 2FKZ, 2MV, 2NH, 2RI, 3APY, 3BK, 3BUR/A, 3IS, 3WW, 3ZK, 5BM, 5GX, 5J0, 5PP, 5RP, 5WP, 5YV, 6MN/A, 60S, 6VD, 6VX, 6XM, 8AL, 8SJ, 8UZ, 8VN, 8WV.

G6HD, 40F Wickham Road Beckenham, Kent.

Worked: G2AUA, 3ABA, 8WV.

Heard : FBNW, G2ADZ, 2HX, 3BUR/A, 3IS, 3WW, 4LU, 5L0, 5PP, 5RP, 6DH, 60S, 6KL, 8UB. (M.A.W.E. No. 3.)

latest, a crystal controlled job into AR88. This last uses EF54 RF, EC52 cathode - coupled mixer and EF50 trebling tritet with 6 me crystal and further EF50 trebler to 54 mc. G5RP asks us to mention that he QSL's 100 per cent. and will send one


View of an 829 PA for 144 mc, as designed by G6VX.

direct by return of post to anyone who hasn't had one.

G2HDY (Roehampton) found it " just murder " on the Sunday evening of M.A.W.E. No. 3, the QRM being the worst ever experienced on five metres !

He heard at least 80 stations during the week-end, including much GDX. G5RS (Guildford) has been putting out a useful signal from his 3 -element beam 12 feet high, and worked G5GX for a good GDX contact on May 10.

G2NH (New Malden) and your earnest conductor are having a friendly race in the stations worked (but not necessarily QSL'd) marathon. We think we are leading by a few at the moment. G2NH's latest score (to reach us) is 251, while we have 257. Our QSL's received amount to 170 which is just two-thirds of the total worked. G2NH also found the QRM tough on May 9, and as a contribution to easing the trouble he is temporarily moving higher up.

The Clubs Membership of the Fiveband Club is

growing steadily, as will be seen from the second list of members herewith. We shall be organising some club events in the next few months and members will be notified of these in due course.

Applications for the VHF CC have also started coming in and we print the list of founder members this time. Several correspondents have criticised Rule 2 (see page 191 last month). When it was decided to introduce this rule, we were of course, expecting that differences of opinion might arise and very careful consideration was given to the point. It was felt that the man who is keen enough to build and operate portable equipment should be rewarded. In addition, such enthusiasts have frequently provided the stay-at-homes, like ourselves, with new counties. Further, some 5 -metre home stations are in poor locations, while others start with a tremendous advantage. To permit portable contacts to count allows the operator who for many reasons cannot work out from his home location to prove his zeal and ability by collecting his QSL's by portable work. The primary object of both Clubs is to encourage VHF work, and although we want to set a high standard for the VHF CC, to make its conditions of membership too difficult will lead to discouragement and the defeat of its objectives.

We are well aware that spivs and drones will always find the loopholes in any set of rules ! Some portable stations have, of course, been combined efforts rather than one-man expeditions, so we simply ask those


who have worked portable not to include cards for such contacts if the bulk of the operation has not been their own personal effort. In other words, the individual will know very well whether or not he has earned the card within the letter and spirit of the rules.

Rule 3 (QSL'ing 100 per cent.) has also been criticised as being insufficient. Expul- sion of offending members has even been suggested. Well, we hope it won't come to that, but if you see a station listed who has not replied to your QSL, write him direct and let us know if there is no result within 14 days.

A complete list of all members of VHF CC will be published monthly (space permitting) and we shall be pleased to add in brackets the total number of QSL's

THE FIVE BAND CLUB Secretary : E. J. WILLIAMS, B.Sc., G2AC

SECOND LIST OF MEMBERS

G5BY H. L. O'Heffernan (Thurle- stone, S. Devon)

GSBD A. C. Simmons (Mable- thorpe)

GSLY Miss C. Hall (Lee -on - Solent)

G2AJ R. Joss (Hendon) G6VX M. Mason (Hayes, Kent) G3ABA L. J. Kennard (Coventry) G2DBF J. F. Squires, M.B.E.

(Bournemouth) G2MR W. J. Thompson

(Surbiton) G2BS C. S. Anderson

(Sunderland) GSGX H. M. Rix (Hull) G3ALD G. W. Spivey (Hull) G3WW R. F. G. Thurlow

(Wimblington) G2KI G. A. Spencer (Walton -on -

Thames) G5RP E. Wake (Abingdon) G5LQ J. Tovell (Chiswick)

G5UM J. H. B. Hum (Knebworth) G3WS F. S. A. Jenkins (Romford) G2RI L. Ridgway (Leicester)

G3BLP J. Haydon (Selsdon)

GM3OL G. Percy (Dumfries) G8UZ A. J. Marriott (Sutton-in-

Ashfield)

received. Note, however, that we shall want to see the extra cards at the 150 and 200 marks-but until you reach those figures just let us have your monthly score. Another point-it would help a lot if all applicants would enclose with their hundred cards a complete list of the calls.

We would like to address a word or two to those who live in out-of-the-way spots from where 100 contacts are unlikely. We do appreciate this factor, but hope it will not prevent joining the Fiveband Club and trying for the VHF Century Club. If you can suggest any other standard by which we can assess VHF achievement, please let us have it. In particular, send along regular reports and lists of calls heard and worked and we can promise you a fair share of our quota of space.

Short Ones A number of interesting reports were

almost too late to catch this, so can only be covered very briefly. G2FCJ (Chiswick, London) writes for the first time ; he has a Type 27 into an Eddystone 640, and the Tx frequency is 59'2 mc .. G6HD (Beckenham) found GDX conditions greatly improved during the month, and for him M.A.W.E. No. 3 produced a total of 77 stations in 20 counties . G6VD. (Leicester) has achieved 15C on 59 mc for ten months' spasmodic operation, using a pair of N-S/E-W dipoles ... G8UZ (Sutton-in-Ashfield) has pulled up to 29C, but G3BW-worked several times by his neighbour G3APY-still eludes G8UZ ... G4LU (Oswestry) has worked or heard a number of new stations and is after G4RX for another county . G4RO (Welwyn) has caught up on his late start on the band with 110 stations now worked and five new counties, and found conditions excellent for M.A.W.E. No. 3, when 60 stationed were logged at G4RO.

G5BY found spor-E openings on May 10, when IRL was S7 on 59 mc 1400-1430, and a BC harmonic came up on 58'5 mc, 1730-1850 BST ; no amateur signals were heard. . GM6WL (Glasgow) reports that he is on 59.9 mc practically every evening 2000-2359 BST, and works G3BW at 100 miles.... G2CIW (Brentwood) has found general conditions good, and also traced brief spor-E openings on May 11

and 12, both about 1315 BST.... G2AJ (Hendon) was reported heard by F3PD (Paris) on the evening on May 15, and F8NW (Boulogne) was worked by G2AJ on May 14 and 15.... On the evening of May 18, G2XS (Kings Lynn) showed up for Norfolk and was worked by G6VX ;

as_,G2XS was reported to be using a g-


wave vertical wire on 58.8 mc, a number of keen county -men promptly rigged up verticals and went after him ! G2XS is there around 2300 BST, almost nightly.

. ZS6GX reports very regular reception of Alexandra Palace TV in Johannesburg.

On July 4, G3PZ will be /P in Hereford- shire to give us a new county, from a site 1,000 ft. a.s.l. . . G3APY (Kirkby) now has 32C with 149S worked, but was too late to catch the Panel this time ; he found conditions good again on May 18, hearing F8NW and working G5GS (Grimsby), G5JO (Cambridge) and G2XS (Kings Lynn). . On May 17, G3DA (Handworth) heard F9BG and OK31D- so the Europeans are there all right. ... G4AP (Swindon), inactive for about a month, is on again now, and, mentioning that he has been rather lax with QSL's, asks anyone wanting his card to write and it will be forwarded without delay. ... G2FQP (Ramsey, Hunts) is another up for a new county, and has started making local contacts.... W1PPH/MM was heard on 50 mc by G6DH when 200 miles west of Naples on May 10.... On May 13 and 15, spor-E was evident to about 55 mc, and FA8IH and OK3ID were heard on 50 mc.

Calls Heard We were very glad to see so many lists

for this issue, but once again would ask that they be set out on separate sheets, headed callsign and address, with operating period and other data below the list ; all callsigns should be in numerical and alphabetical order and divided into "heard" or "worked" sections -in fact, as we have so often said, please make up your list in exactly the same form as it appears in print ; it makes the work of preparing the Calls Heard sheets very much tidier and quicker.

Magazine Activity Week -Ends The following are dates of forthcoming

M.A;W.E.'s : June 12-13, July 10-11, August 7-8, September 11-12. It is hoped also to organise a full-dress Contest in October.

Conclusion Final date for next month's reports is

June 18. The address is, as usual, E. J. Williams, G2XC, Short Wave Magazine, 49 Victoria Street, London, S.W.1. Thanks, again for the load of mail and BCNU, July 7 in the next issue.

British Old -Timers' Club Consolidated Membership List

Since the third Membership List was published in April, bringing the total to 100, nine more members have enrolled. Here they are, in order of "seniority'

Capt. G. F. Steven - (GM5BA), 1910 ; G. W. G. Benzie (VU2BGIGM4KU), 1912 ; H. B. Dent (G2MC), 2AV in 1919 ; S/L L. D. G. Morrison (G2BU), 5JJ in 1923 ; G. S. Samways (G6OH), 1923 ; H. E. Smith (G6UH), 1926 ; D. E. Scarr (G6XX), 6DR in 1926 ;

L. W. Gardner (G5GR), 1927 ; R. A. Minter (GSRM), 1928. -

And here, so that all who belong to the B.O.T.C. shall have a reasonable chance of recognising other members when on the air, is a consolidated list, making the total of 109 collected up to the present date :

G2AD, 2AK, 2BC, 2BI, 2BN, 2BU, 2CN, 2DC, 2DX, 2DY, 2FK, 211P, 2IP, 2JC, 2JZ, 2KF, 2LP, 2MC, GM2MG, G2NH, 2NM, 2PC, 2QB, 2SK, 2SU, 2TG, 2VU, 2WD, 2WT, 2XV, 2YI, 2YN, 2ZC ;

G3ASP, HIT, 3JZ, 3SD, GW3ZV ; G4FX, 4KI, 4M11 ;

GM5BA, G5BD, SBK, SBS, SBY, 5DM, 5F11, SGG, SGR, GI5HU, GI5HV, GMSJK, GSJM, SKR, 5KP, 5LH, SLJ, SLY, SMF, 5MM, 5NO, SPO, 5PS, 5QA, 5QB, SQP, 5RM, 5RS, 5RZ, 5TV, 5UF, SUX, 5UY, 5XD, 5YN ; G6BB, 6CI, 6DY, 6FI, 6F0, 6HR, 6I0, 6KM, GM6LS, G6MC, 6MI, GM6MS, G6NF, 6NK, 6011, 60M, 600, 6FF, 6PG, 6QB, 6QC, 6UH, 6UT, GI6WG, G6XD, 6XL, 6XS, 6XX, 6YQ, 6YU, GI6YW; VE3BWY ; VU2BG.

Remember that the Old Timers' Dinner is to be held in London in the early autumn ; this was announced on p.110 of our April issue. If you wish to be there, please notify either the RSGB or the Short Wave Magazine not later than June 30. B.O.T.C. members should write us direct, and other old timers, not in- tending to become members of the Club, should inform the RSGB if they want to attend. And if you wish to join the B.O.T.C., your eligibility is determined by clause (b) on p.110 of our issue for April -so let us know.---L.H.T.


Superhet for 420 mc Designed and Constructed by G4LU

(Here, on a practical basis, is a first solution to the problem of a receiver for our coming 70 cm band. Employing accepted techniques and not involving any circuit complications,

it is a sound design upon which many constructors will be basing their ideas.-Ed.)

EING half -prepared for the release of 1.3 the new 420 mc band, thoughts were turned to the question of obtaining a suitable receiver. Enquiries failed to dis- close a suitable ex -Service type for modification, and it was decided to attempt the construction of one. If amateur technique on the new band progresses with the same rapidity as on the lower frequency bands anything of the super -regenerative kind would soon be outmoded. A superhet was therefore decided upon and the simplest form of such a receiver-consisting of a mixer and single channel IF amplifier- was made the basis of the design. An IF of 40 mc was chosen because this has been standardised in radar gear and the amateur who has a suitable IF strip could use it in place of the IF amplifier described later.

The valve line chosen consists of two EF50 amplifiers at 40 mc, followed by an EF50 leaky grid detector. A 6AC7 high - gain audio stage and 6J5 output stage are used after the detector valve, the 6J5 providing sufficient output for headphones or small speaker.

By careful attention to design and layout a stable IF amplifier was made and formed the foundation for the receiver. The whole was conveniently assembled on a chassis 8 in. square by 2 in. deep, which left sufficient room to mount the mixer and oscillator circuits as a separate sub- assembly. This mode of construction was adopted because of convenience in experimenting and if needs be the mixer and oscillator can be used separately as a converter ahead of a receiver tunable to 40 mc.

Mixer and Oscillator Assembly The mixer and oscillator circuits are

mounted on a 1 --in. brass panel, 5 -in. by 6 -in., ensuring rigidity and hence mechanical stability of the oscillator circuit. The panel is fixed to the main chassis by four 4 BA bolts, and can easily be removed by unsoldering three leads (i.e., HT, LT and output). A 955 acorn triode is used as a diode mixer and the anode -grid capacity of this valve is utilised as the

coupling capacity from the mixer circuit to the first IF transformer.

Another 955 acorn triode is employed as the local oscillator in an ultra-audion circuit ; stray capacity is relied upon for the coupling to the mixer. The mixer input circuit consists of a capacity -loaded quarter wavelength transmission line, and the aerial is tapped on one line and the mixer grid on the other, as shown in the circuit diagram. The lines are roughly 3 in. in length, spaced 1 in, apart and are made of 4 -in. diameter brass rod. These lines are mounted vertically in a brass block, in. thick, which i -s screwed to the base plate. The block is split along the common diameter of the rods and the two pieces are secured by a couple of 4 BA bolts. This facilitates easy removal of the lines during the cut -and -try process of the initial tuning.

The tuning condenser consists of 2 -in. diameter brass discs mounted on the open ends of the lines. One disc is made adjustable by mounting it on a length of 4 BA studding, so that the separation of the plates may be varied for tuning purposes. The studding is attached to an insulating rod to reduce hand capacity effects.

The tapping points on the lines are made by small brass clamps which can be tightened by an 8 BA bolt in each clamp. The mixer grid connection of the valve holder is a very short length of flexible copper strip which is soldered direct to its respective clamp. The cathode and earthy heater connection are likewise soldered to a short length of copper strip which in turn is fastened to a small brass block. This block is secured to the base plate by a single 4 BA bolt which runs in a slot ; the height of the mixer grid tapping point on the line can thus be adjusted.

Oscillator Circuit The oscillator tuned circuit also consists

of a capacity -loaded transmission line. The lines comprise two lengths of 14 SWG tinned -copper wire about 2 in. long and spaced 1¡ in. apart. The tuning condenser is of the butterfly type with a maximum


Fig. 1. Circuit of G4LU's 420 -mc receiver; the construction is fully described

in the text.

capacity of 12 µµF + 12µµF. It is a well- known component, having been incorporated in a war -time IFF unit and is fairly easily obtainable from surplus equipment. This particular method of tuning was decided upon after a number of different ideas had been tried but dis- carded either due to being noisy or having restricted tuning range. The circuit described operates lower than the signal frequency and provides a range slightly in excess of that required to cover the band. The lines are soldered direct to the condenser lugs at the one end and to the valve -holder tags at the other. The condenser itself is mounted on a piece 'of material, Keramot or Paxolin, and the spindle is driven through a flexible coupler from the dial. This construction ensures minimum stray capacity to earth. The valve -holder is mounted away from the base -plate by two long 4 BA bolts through spacers so that the plane of the lines is

parallel to the baseplate. It is suggested that the valve -holder be not finally fixed to the base until the actual length of the lines has been determined on test to give the required tuning range. In the writer's model, the valve -holder spacers took the form of a block of Keramot through which two 4 BA clearance holes were drilled. The middle of this block was cut away to clear the bottom of the valve and two soldering tags were mounted on it to form anchoring points for the filament chokes. A tag was also mounted on the tuning condenser support and the anode choke was connected between it and the condenser connecting lug. The grid leak is

Table of Values Fig. 1. Superhet for 420 me

Cl = C2 =

C3, C14 = C4, C5, C9, C13 =

C6, C7, C10, C11 -- C8, C12, C15; C17, C20 =

C17, C20 = C16, C18 = C19, C21 =

C22 = C23 =

All condensers rated RI, R4,R7 =

R2, R6 = R3, R5

R8 = R9, R10, R15, R17 =

Rll, R16, R19 = R12, R13 = R14, R18 =

RFC =

Tl, T2, T3 L

VI, V2 V3, V4, V5

V6 V7

250v HT

12 + 12 µµF (see text) see text 100 µµF 3-30 µµF trimmer 001 µF mica -01 µF mica 01 µF mica 0.5 µF paper 50 µF, 12 v. electrolytic 1 µF paper 8 µF electrolytic 350 -volt DC working 20,000 ohms, 4 -watt 200 ohms, z -watt 10,000 ohms, 4 -watt 2 megohms, :-watt 100,000 ohms, 4 -watt 50,000 ohms, 4 -watt 500,000 ohms, 4 -watt 1,000 ohms, i -watt 10 turns, 4 -in. diam., á in. long, 22 SWG enam. see text LF choke 955 acdrn EF50 6AC7 6J5 or L63

Top view of the receiver showing construction of the oscillator side.

wired between the base -plate and the other condenser lug. The tuning dial is mounted on a metal panel as a precaution against hand capacity effects.

The IF Amplifier The construction of the IF amplifier is


quite orthodox and should not be difficult. The IF transformers, which are home made, are wound on *-in. diameter Paxolin tube. The windings are terminated on short lengths of 14 SWG tinned -copper wire which are a tight fit in holes drilled through the formers. No lugs are provided for the coupling coils on T2 and T3 because they could be wired conveniently to the appropriate points in the circuit. The formers are spigoted into blocks of Paxolin for mounting purposes, and a slight smear of shellac on the former will

of the valve. The internal screen and suppressor connections are each joined to the spigot connection which is connected to a soldering tag fitted under one of the valve -holder fixing screws. The screen grid and anode by-pass condensers are returned to this point. The cathode by-pass condenser is returned to an adjacent earthy pin and the earth return of the grid circuit is made to this same pin. The grid tuning condensers on Tl and T2 are wired direct to the appropriate pins on the valve -holder.

The single -point earth feature is also used in the 6AC7 stage. The 6J5 audio stage could be replaced by a 6V6 or 6F6 for speaker working, although a 6J5 will operate a 5 -in. speaker quite well. The volume control circuit is a little unusual, but here again the circuitry was dictated by what was available. The 50,000 - ohm potentiometer was rather small to be used in the grid circuits of the audio stages but was large enough to be used in the position shown. A more cönventional arrangement might introduce the possibility, of hum pick-up on the longer grid leads thereby entailed.

Lining Up The Receiver Lining up the receiver

is as easy, but perhaps not quite so convenient, as lining up a lower -frequency

14 SWG tinned copper anchoring tags

Mixer anode

Paxolin tube

T. IO turns 6 24 SWG enam.

10 turns 24 SWG enam.

-F-Paxol i n

base

L6 BA clear fixing holes

DETAILS OF TI

,,.

Anode

Grid

Coupling winding 2 turns

push -back wire / HT

sr 10 turns 24 SWG enam.

-s-Paxolin base

Fixing hole'tapped 2 BA

DETAILS OF T2 & T3

Fig, 2. Making the IF transformers Ti, T2 and T3 for the 420 -mc receiver.

attach it firmly to the base. These IF transformers are not represented as ideal but they will work, although the performance of the receiver could no doubt be further improved by spending a little time on producing less makeshift transformers. Suggested lines of experimental work could be the provision of tuned primary windings as well as the tuned secondary on T2 and T3 and the use of a Faraday shield between the primary and secondary windings so that the coupling is entirely inductive. The writer was limited in his scope in these experiments by attempting to build as much as possible from equipment at hand and all the available trimming condensers were used up in the present design.

Shielding is provided between the input and the output circuits of the EF50 valves by a screening partition placed across the centre of each valve -holder. A cut-out is necessary in each screen to clear the spigot

Top view of the Rx with IF valves out. The first IF transformer and mixer tuned circuit are in the foreground,

and the oscillator circuit to the rear.


receiver. An oscillator with 40 mc output is required for the IF amplifier and the procedure is conventional in that the detector grid circuit is first tuned, then the second IF amplifier grid circuit and finally the IF input circuit. The writer used the second harmonic of an oscillator working on 20 mc for this part of the work with the advantage that its frequency could be checked with reasonable accuracy on a communications receiver. Alignment is facilitated if the oscillator is modulated by an audio tone.

The next step is lining up the local oscillator so that it covers the proper frequency range for the 470 mc band. Lecher wires or a wavemeter are a "must" for this job. If lecher wires are employed sufficient output -can be obtained from the oscillator to light a 60 mA bulb at the current antipodes, or alternatively a low - reading thermo-milliammeter can be used. The length of the oscillator lines is adjusted until the oscillator covers a range slightly in excess of 380-420 mc; having determined the correct length the valve -

holder can then be fixed to the base plate. The alignment of the signal circuit

requires the use of an oscillator capable of operating in the proposed band. The signal is tuned in on the oscillator control and the signal circuit tuning condenser is adjusted until the signal peaks in strength.

Under -chassis view. Note screening partitions across the EF50 vaiveholders.

The input lines may require pruning to obtain a tune over the full range of the band. The writer's lines started off 6 in. long, and were adjusted á in. at a time until a satisfactory length was obtained. This tuning operation is carried out with the mixer grid tapped as far down the line as possible. A dipole aerial can then be connected to the receiver input socket and the aerial and mixer grid tappings on the lines adjusted to produce maximum signal. The tuning range of the circuit should again be checked and any necessary adjustment made to the line length. During the alignment of the signal circuit the test oscillator had to be removed to an adjacent room in order to reduce its field strength, even though no aerial was connected to it. A screening cover over the RF assembly was found necessary to prevent direct pick-up on the signal lines from masking the aerial tapping adjustment.

Performance Little can be said about performance,

since obviously "on the air" -tests cannot be conducted until the band is released. As an experiment the test oscillator was fitted with a simple modulator and microphone and was set up about 60 ft. from the receiver. The receiver was connected to a dipole and headphone. The over-all gain of the circuit was sufficient to set up a howl. due to audio feedback between the headphones and the microphone. The oscillator tuning control is not difficult to use and tuning is quite as easy as on a lower frequency receiver.

It is hoped that this description of a simple receiver, constructed mainly from spare parts and with the minimum expense may suffice to stimulate interest in the new band. CU on 420 mc, OM?

AUSTRALIAN COMMENT

In the course of a recent airmail letter, a VIA correspondent remarks as follows :

"In my opinion, radio in Australia is a pricked balloon from the trading angle, though it is still good business for the commercial broadcasting people feeding moronic material to receptive illiterates. If you know of any G's thinking of leaving home to start in radio here, tell them to think again ; there are neither homes nor security to be had and to make more than average money one must be a lottery winner. One G I know here (in Australia) rues the day he came...."

The "640" Presentation. G2AJV (left) receives his Eddystone Amateur Band Receiver from the Mayor of Grimsby, Councillor W. B. Bailey, J.P. G5GS, the chairman of G.A.R.S., is on the Mayor's immediate right, and on the right n the photograph is G6XJ, Sales Director of Messrs. Stratton & Co., Ltd. (Courtesy Fearnley Photos)

Grimsby Occasion Presentation of the Eddystone

"640" Receiver

ON the evening of Friday, May 7, the Mayor of Grimsby (Councillor W. B.

Bailey, J.P.) presented the Eddystone "640" Communications receiver won by R. C. Jennison, G2AJV, in the home section of the recent Essay Competition organised by Stratton & Co., Ltd. The winning entry appeared in the May issue of the Short Wave Magazine.

To mark the occasion, the Grimsby Amateur Radio Society (which has been in existence for 17 years) organised an Amateur Radio exhibition, which was open to the public for the whole evening. A very good show resulted, with many excellent' examples of amateur -built equipment. Much interest was taken in the actual operation of the Grimsby Club station G3CNX/A, which was active on 3.5 me and made many contacts during the evening.

A large number of people witnessed the presentation. G5GS acted as chairman, and expressed appreciation of the honour conferred on G.A.R.S. by the Mayor's presence. Mr. A. C. Edwards, G6XJ, Sales Director of Stratton's, explained the nature of the Competition and gave some interesting details regarding the efforts made by his firm, over a period of many years, to look after the requirements of amateurs.

The Mayor prefaced his own remarks by enquiring if the Birmingham contingent had come to scout for football talent- Grimsby finished bottom of the League table ! He congratulated G2AJV on his success in the "640" Competition, and mentioned how proud they were that he is a citizen of Grimsby.

Following the presentation, the Mayor was escorted round the Exhibition and was persuaded to speak over the air to G4GI (Boston, Lines.) from G3CNX/A.

Altogether, a very successful and well - organised affair, reflecting great credit on G3TZ, Secretary of G.A.R.S., and those who assisted him with the committee work that such an event entails.


ete acá Ihete Corrigendum

Another of these El' errors crep' in, drat 'em. On p.172 of G5UM's article in the May issue, what purports to be an energy distribution curve in Fig. 2 is obviously wrong ; the curve as shown represents neither voltage nor current for that particular element length. Fortunately, this drawing slip in no way affects the argument, since the system G5UM suggests can still be fed at current at that point. Thanks to the eagle-eyed who showered us with post cards about this -but, again, it was one of those we noticed when it was too late !

Piece of Cake It really is a piece of cake, this DX

racket. For instance, you want a contact with W7 so, of course, you call "W7". Not if you know what's what, you don't. One little "CQ W7" is guaranteed to bring back at least a couple of UA1's, possibly an I and in any case half the East Coast of the USA.

On the other hand, should you be silly enough to reply to a CQ from HP2X, you'll have your ears blown in by a bird in Salt Lake City, madly anxious to shake your hand across the oceans. But just try calling Salt Lake City, and see what happens.-From Sunderland Radio Society Newsletter.

Change of Name-Mullard The great concern which for many years

has been known as the Mullard Wireless Service Co., Ltd., changed its name to Mullard Electronics Products, Ltd., with effect from April 22. Mullard's originally started in 1920 as the Mullard Radio Valve Co. and by 1925 had made such progress that a separate company had to be formed to handle the products of the valve manufacturing side of the business. In thé last few years, the firm has entered into many activities in the wide field of electronics, and the manufacture of valves is now only one of Mullard's interests.

DX Operating Manual Elsewhere in this issue is an announce-

ment regarding our new DX Operating Manual, the first publication of its kind originated in this country. Written and produced by the staff of the Short Wave

Magazine with L. H. Thomas, M.B.E. (G6QB), our Assistant Editor and well- known DX writer as chief contributor, it deals with every aspect of DX working. We dare say that the DX Operating Manual will in due time become the standard work of reference on the subject. Chapter headings are : Amateur Operating Pro- cedure, Using the Bands, What IS DX, How to Work DX, The QSL System, Competitive Amateur Radio, and Countries of the World.

The first printing will become available very shortly after this appears. In Magazine format, of 40 pp. on art paper with colour cover, the DX Operating Manual can be obtained direct from us at 2s. 6d. (2s. 8d. post free). Write The Circulation Manager, Short Wave Maga- zine, Ltd., 49 Victoria Street, London, S.W.1.

K2UN-United Nations At any time from now on, you may hear

or work K2UN at the HF end of the14 me 'phone band. K2UN has been specially established as the United Nations Amateur Radio station and will operate with the object of furthering world accord and the cause of the United Nations through the medium of Amateur Radio.

On May 13, K2UN was on the air and in QSO with a G8, one of those speaking from K2UN being ex-G2AIS, our American correspondent. He was also present at the official inauguration of K2UN on May 17. In writing us about the station and its objectives, Peter Lovelock mentions that during the initial testing period, K2UN was called by many operators who thought they were on to a new country !

We hope to be publishing photographs and some more information about K2UN when further details are received from America.

A Shadow Cast A new one to show up is ZNP8,

Jerusalem, on 14320 kc, heard by G8NY (London) at 1700 on May 14, testing with the BBC and asking any listener receiving the signal to report it to the Corporation. G8NY did so, and was apparently first with the news to the BBC, who were also asked to QSL via Cable & Wireless, Haifa.


NEW QTH's

This space is available for the publication of the addresses of all holders of new consigns, or changes of address off

transmitters already licensed. All addresses published here are automatically included in the quarterly Issue of the Call Book in preparation. QTH's are inserted as they are received, up to the limit of the space allowances. Please write

clearly and address on a separate slip to 0TH Section.

G2AAX

G2API

G2AQI

G2AUC

G2AUP

G2AYY

G2BNF

G2BS

G2CTC

G2CVO

G2DWM

GM2DYP

G2FRY

G2HN

GW3ACW

G3ALC

GM3AOR

GW3AZQ

G3BET

G3BNV

G3BRV

GM3BST

G3BXU

G3BYY

GM3BZJ

G3CEB

G3CEU

G3CFM

G3CGD

G3CHW

G3CIK

G3CIR

G3CJM

G3CJU

G3CNU

G3CTX

A. W. G. Anderson, 93 Maybury Road, Hull, Yorks.

H. Batty, 1 Marshall Square, Upper Denby, Huddersfield, Yorks.

J. A. Ekin, 43 Bradley Boulevard, Sheepridge, Huddersfield, Yorks.

A. J. Brennan, 34 Lowestoft Street, Rusholme, Manchester 14.

H. Taylor, 18 Colin Street, Barnoldswick, Yorks. (Tel.: Barnoldswick 412.)

T. Pollard, 6 Rosehill Mount, Burnley, Lancs.

W. S. Panter, 23 Cecilia Road, Feniscliffe, Blackburn, Lancs.

C. S. Anderson, 9 Marina . Avenue, Fulwell, Sunderland, Co. Durham.

S. R. Cooke, 18 Cross Flatts Avenue, Leeds 11, Yorks.

F. Osborn, 13 Mount Echo Drive, Chingford, London, E.4.

H. E. Hardy, 4 Market Lane, Burnt Oak, Middlesex.

N. H. McLean Ross, 64 Thirlestane Road, Edinburgh 10.

A. Shillito, 170 Birkin Avenue, Hyson Green, Nottingham.

E. Howell, 31 Sheldon Road, Chippen- ham, Wilts.

J. McHarg, Glengyle, Penrhos Drive, Bangor, North Wales.

P. C. Spence, The Poplars, Braunston Road, Oakham, Rutland.

R. B. Brown, 12 Abbotsford Place, Dundee.

C. Jones, -12 The Drive, Gilfach, Bargoed, Glam., S.Wales.

S. Russell, 1 Raven Street, Hedon Road, Hull, Yorks.

F. Exeter, 2 Abbey Gate, Minster, Sheerness, Kent.

R. C. Bennison, 29 Clarence Square, Brighton, Sussex.

J. B. Tuke, Radio Station, Benbecula, Outer Hebrides.

W. E. Priest, Delabole Radio Service, Delabole, Cornwall.

E. W. Elliott, 51 Kenworthy Road, Homerton, London, E.9.

B. Woodward, No. 2 Cottage, Renfrew Airport.

G. A. Garbutt, 52 Scruton Avenue, Durham Road, Sunderland, Co. Durham.

N. F. Wilshire, 13 The Tene, Baldock, Herts.

C. W. Henwood, Redhouse, Bell Weir Park, Wraysbury, Bucks.

J. J. Yeend, 30 St. Lukes Road, Chelten- ham, Glos.

D. V. Newport, 250 St. Johns Lane, Bedminster, Bristol, 3.

H. D. Romer, 96 Mortlake Road Kew, Surrey.

W. Caton, 25 Valetta Grove, Plaistow, London, E.13.

D. Clapp, 62 Brodrick Road, London, S.W.17.

A. W. Grimsdale, 164 London Road, Newbury, Bucks.

E. B. Davis, Knowle, Valebridge Road, Burgess Hill, Sussex.

W. M. R. Luckett, 47 Leamington Road Villas, London, W.11.

G3CUJ M. G. Bulmer, 16 Bentley Grove, Cottingham Road, Hull, Yorks.

G3CVG S. Jackson, 6 Marlborough Street, Plumpton, Wakefield, Yorks.

G3CVT C. S. Vane -Tempest, Woodsgift, Gander Hill, Haywards Heath, Sussex.

GW3CZN Mai. A. G. Acland, The Cottage, Narberth Road, Tenby, Pembs.

G3DAY G. R. Sanderson, 73 Queens Drive, West Derby, Liverpool 13.

G3DBF F. Knowles, 8 Victory Drive, Forest Town, Mansfield, Notts.

G3DBI F/L J. Douglas, 32 Mytton Road, Whalley, Blackburn, Lancs.

G3DBI/A F/L J. Douglas, Empire Radio School, RAF Debden, Saffron Walden, Essex.

G3DBO J. C. Brown, Shaw Cross, Kirkheaton, Huddersfield, Yorks.

G3DDQ V. I. Bowden, 11 Alpha Road, Cambridge. G3DER F/L J. P. Wieson (ex-VS1BO), RAF

Compton Bassett, Calne, Wilts. GM3DGD J. Dickie, 5 Dunedin Terrace, Clydebank,

Glasgow. G3DGG W. A. Henson, 12 Fitton Way, Chippen-

ham, Wilts. G3DHC F. Boyes, 31 St. AIbans Road, Blackpool,

Lancs. GM3DIID G. W. D. Brown, 11 Craigcrook Terrace,

Blackhall, Edinburgh. GM3DHR I. McK. Goodall, 5 Burghlee Terrace,

Loanhead, Midlothian. G3DIC C. H. Bullivant, 25 St. Fillans Road,

London, S.E.6. G3DIO D. Counsell-Davis, 58c Lexham Gardens,

London, W.8. GM3DIQ W. C. Bradford, 39 Sinclair Street,

Stevenston, Ayrshire. G3DIR F. W. V. Buckland, 24 Norton Crescent,

Baldock, Herts. G3DJQ B. H. T. Oliver, Wychdene, 131 Church

' Lane, Handsworth Wood, Birmingham 20.

GM3DJT J. M. Mitchell, 10 Regent Street, Porto- bello, Midlothian.

G3DKF R. R. Stringer, 106 Northfield Road, Coventry, Warks.

G3DLA W. S. Drake, 73 Kempshott Road, London, S.W.16.

G3DLB P. H. Draycott, 47 Longreach Road, West Derby, Liverpool 14.

G3DLO J. E. Wightman, 35 Swift Way, Lutter - worth, Rugby, Works.

G3DMU S. Thompson, High Street, Crowle, Scunthorpe, Lines.

GM3DNQ D. H. McLean, 238 Union Grove, Aberdeen.

G3DNT B. N. Gregory (ex-D2AQ), Lower Terrace Road, Town Head, Tideswell, Buxton, Derbys.

G3DNY R. G. Partridge, 37 Beechwood Avenue, Thornton Heath, Surrey.

G3DNZ J. K. Robinson, 55 Giles Road, Langley, Birmingham.

GW3DOF M. B. Skinner, 29 Victoria Street, Cwmbran, Newport, Mon.

G3DOG R. F. C. Crowther, 8 Gloucester Court, London, W.3.

G3DOQ C. P. Pirnie, 62 Marina Drive, West Monksea Lon. Whitley Bay, Northumbs.

G3DOZ J. D. Smith, 9 Greystoke Park Terrace, London, W.5.

GM3DPK W. McGowan, 16 Barnhill Road, Macduff, Banffshire.


G3DRL J. M. Willies, The Wilderness, Grove Road, Holt, Norfolk.

G3DRN E. G. Allen, 65a Melbury Gardens, Wimbledon, London, S.W.20.

G3DYQ P. R. Smith, 84 Orchard,Avenue, Lancing, Sussex. -

G4DH G. R. Pearson, 102 Overdale, Ashtead, Surrey.

GSVP/A G. F. Kitchen, Royal Aircraft Establish- ment, South Farnborough, Hants.

CHANGE OF ADDRESS G2ALO R. P. Munn (ex-G2FUV), Whitenest,

Sandgate Lane, Storrington, Sussex. G2ALO, A R. P. Munn, 163 DoIlis Hill Lane,

London, N.W.2. G2BU S/L L. D. G. Morrison (ex-VQ4HBA),

Twyford Hall, Dereham, Norfolk. G2NU A. J. Hall, c/o Tropical Radio Co. Ltd.,

Senior Works, Church Street, Staines, Middlesex,

CARDS IN THE BOX

If your call is here, it is because we hold QSL cards for you and have not got your full postal address on file. Please send a stamped addressed envelope, about the size of this page, with your name and callsign, to BCM/ QSL, London, W.C.1. ; the cards will be forwarded on the next G clearance. Should you wish your address to be published under "New QTH's," please mention it at the same time.

2ACZ, 2ADL, 2ADM, 2AII, 2ALB, 2AMA, 2AOF, 2AUU, 2BFB, 2BIP, 2BMW, 2BPB, 2BQ, 2BTU, 2BWL, 2CJ, 2CQ, 2CUA, 2DGF, 2DKV, 2DTG, 2FAF, 2FFP, 2FIG, 2FSO, 2FTV, 2HAI, 2HAV, 2HBH, 2HDC, 2HDO, 2HZF, 2RY, 2ZL, 3AB, 3ACP, 3ADB, 3AKJ, 3ALA, 3ALP, 3AM, 3AMW, 3AN, 3ANF, 3ANX, 3APD, 3ARG, 3ART, 3ASX, 3ATY, 3ATZ, 3AUA, 3AUP, 3AVV, 3AXT, 3AXV, 3AXW, 3AYS, 3BCQ, 3BDI, 3BFG, 3BGN, 3BHW, 3BJ, 3BJU, 3BKH, 3BLR, 3BMV, 3BMY, 3BMZ, 3BNU, 3BOS, 3BPJ, 3BRE, 3BRK, 3BUD, 3BVE, 3BYX, 3CAB, 3CAI, 3CBA, 3CDQ, 3CEV, 3CLB, 3CNJ, 3CNO, 3CPR, 3CQC, 3CQK, 3CTT, 3CUA, 3CVW, 3CWT, 3CXF, 3CXN, 3CXU, 3CXY, 3CYA, 3DAI, 3DCD, 3DDG, 3DDM, 3DEQ, 3DJL, 3DJW, 3DKP, 3FW; 3MM, 30D, 3SZ, 3TP, 3ZC, 4HT, 4JG, 4KM, 4MW, 4NQ, 4PV, 4YN, 5BC, 5BW, 5CH, 5DZ, 5IS, 5JG, 5RX, 5WL, 6GA, 6KL, 60Y, 6PW, 6SP, 6TU, 6VY, 8AU, 8AV, 8FC, 8KX, 8KY, 80H, 8PT, STB, 8UJ, GI3B WV, 3CTU, GM2FVS, 3BTX, 3BUX, 3CXF, 3SA, 4AA, GW2CM, 3AUJ, 3BRI, 3CA, 3DDY.

G3ADI

G3BFC

G3BSL

G3COV

G4QU

GSGW

GSYP

G6PG

G8MP

G8SL

GsuT

N. Ward, Talbot House, Mather Road, Birkenhead.

W. H. C. Wheeler, St. Margarets, Dudsbury Road, Ferndown, Dorset.

E. B. Hardy, Hill Cottage, Dunstall, Burton on Trent, Staffs.

G. B. Woffinden, 11 Lonsdale Place, Whitehaven, Cumberland.

F. C. Mason, The Abbot's Fireside, Elham, Canterbury, Kent.

S. Bowden, Netherton, Barton Hill Road, Torquay, Devon.

J. H. Wood, Woodleigh, Park Road North, Middlesbrough, Yorks.

C. H. Targett, 182 Shepherds Lane, Dartford, Kent.

H. Pilbeam, 25 Hardwicke Road, Reigate, Surrey.

H. A. Smith, M.S.R.E., Relay House, High Street, Braintree, Essex.

B. Challis, Aloha, 43 Dorchester Close, Dartford, Kent.

XTAL XCHANGE

Here are this month's offers :

G3CEM, 49 Warkworth Street, Lemington. Newcastle -on -Tyne. Has 5000 kc crystal. Wants frequency 8000- 8111 kc.

GM3DPK, 16 Barnhill Road, Macduff. Banffshire. Has 7044 kc crystal, mounted. 'Wants 7050- 7100 kc.

SWL, 20 Nixon Avenue, Leeds. 9. Has 3750 and 7225 kc crystals, hollered, with -in. pin spacing. Wants similar, same bands,

but in CW areas. SWL, 47 Braemore Road, Hove, 3 Sussex.

Has OCC Type PS 7083 kc crystal. Wants frequency 7010-7055 kc.

NEW QTH SECTION

With the appearance of this month's "New QTH's" we are almost abreast of the back -log and any now in hand will appear in the next list. We still cannot guarantee, however, that all those received before the July issue will be published in that list.

SMALL ADVERTISEMENTS Readers will hardly have failed to

notice the volume of small advertising we now carry -so much so that we have a spill -over and have therefore decided to apportion a small amount of space in our Short Wave Listener for readers' advertising.

Charges in the Short Wave Listener are :

READERS : 2d. per word, minimum rate 3s. Box Nos. 1 s. 6d. extra. TRADE : 6d. per word, minimum charge 7s. Copy for the next issue, dated July and due out on June 17, must be in hand by June 7 latest, addressed (with remittance) to the Advertising Manager, Short Wave Listener, 49 Victoria Street, London, S.W.1.


The

other

man's

station

ZD4AM

Many readers will have worked or heard ZD4AM-Harold Owen, West African Cacao Research Institute, Tafo, Gold Coast Colony-now home on leave at 2 Campion Avenue, Basford Park, New- castle, Staffs. ZD4AM started as a keen SWL in pre-war days and for years bas been a regular correspondent to our DX features.

The outfit out there is very simple, with a home -built Tx-6V6-6L6-P/P 807 combination-running at about 20 watts PA input from DC mains of a nominal 220 volts. Heaters are fed from a car battery, on permanent float charge by being inter- posed between the refrigerator and the mains.

On the receiving side, ZD4AM has an 8.107, with a ten-year old 0-V-1 as stand- by. On his return from leave, he hopes to add a good VFO and some reliable frequency -measuring equipment.

So far, the station has been operated exclusively on 14 mc, with a dipole cut for that band and slung on bamboos, giving

an E -W run and main directivity N -S; something better is planned for the future to make the most of the 20 watts-the ZD4 licence limit is 25 watts, so efficiency must be the key -note of the installation. Under the conditions outlined, ZD4AM had achieved 64C in 24Z in about 6 months' operation. A card index record is kept of all contacts and QSL's are sent to every station worked for the first time.

Since the Magazine has not yet published a great circle map centred on the Gold Coast (!), ZD4AM "sweated one out from first principles" and is very rightly rather proud of it ; we are glad that it is just visible in the photograph, as we know what labour such a production must have entailed.

Finally, ZD4AM mentions his great indebtedness to another old friend of ours, David Mitchell (GW6AA), now departed for New Zealand, who gave him a generous measure of assistance in getting going and so helping to put the Colony on the DX map.


THE MONTH WITH THE CLUBS FROM REPORTS

Á high level of activity is indicated by the fact that this month we publish reports from 33 Club organisations- for the beginning of the summer season, that figure is quite a record. But, in spite of our repeated adjurations, reports continue to arrive after the deadline (with special requests that we " please squeeze them in "), and at least a dozen have had to be held over again this time.

We give the latest possible date each month for receipt of Club reports for the issue following. As obviously we use a special setting for this feature (in the interests of economy of space), a machine has to be changed over for the purpose of getting it into print ; so soon as that is done, the machine is changed back again, and it is just not possible to accommodate late corners similarly, it is impracticable to open the rules, or borders, round the Secretaries' Address Panel to insert more QTH's after the panel is set. In other words, once the job is done, we cannot make large alterations or additions. We are sure the great majority of Secretaries will agree that this is fair enough.

So please remember : there are only two kinds of Club report-the punctual and the absent ! We are always glad to see every report in the former category, and provided it is in by the due date, will guarantee its appearance. The closing date for the next issue is first post on June 17,

and the address is Club Secretary, Short Wave Magazine, 49 Victoria Street, London, S.W.I-and please keep your report as meaty and factual as possible. And, by the way, we should like to see a few more photographs suitable for this feature.

For the information of Club Secretaries generally, we might also add that the current (June) issue of our Short Wave Listener carries nearly 80 addresses of the Secretaries of Clubs now included on our Active Register.

Stourbridge & District Ama- teur Radio Society.-On May 4 they met at King Edward School to hear a talk on the Moving Coil Pick -Up by Mr. H. H. Jones, the inventor and patentee of the first model, which was made inStourbridge. The talk was followed by a demonstration. Future talks include the subjects of Super - het Receivers and Loud Speakers, and a visit to Droitwich has also been arranged.

Basingstoke District Amateur Radio Society.-A series of lectures on The Oscilloscope and its Applications is to be given by Mr. J. A. Lowe at the Cricketers Inn Hall, May Street. Dates will be announced later.

Thames Valley Amateur Radio Transmitters Society.-At the May meeting Mr. Wiggles - worth of Mullard gave a lecture on Transmitting Valves, covering their operation and the more common failings of their users! The former Secretary, G3JG, has unfor- tunately had to retire on account of ill health, and his successor is G8SM (QTH in panel). The June meeting, on the 2nd, will be at the Car- narvon Hotel, Hampton Court, at which NFD plans will be discussed, and G2CGX will lecture on the Radio Amateurs' Examination.

Reading Radio Society.- Recent meetings have included a Junk Sale (presenting many "weighty" problems to

members), a "Non -Radio Evening," and a lecture by Mr. G. T. Peck on "High Speed Electronic Discharge Flash -Lighting."

North Kent Radio Society.- At a recent meeting Mr. S. C. Tucker (G8DT) was elected President and Mr. J. L. Bowes (G4MB) Secretary. Equip- ment is under construction for NFD, using the call G4MB/P on 1 .7 and 3.5 mc. Future meetings will be held at Free - mantle Hall, Old Bexley, on Monday evenings at 7.30 p.m.

Lothians Radio Society.- This Club, a newcomer to our columns, meets on the last Thursday of each month in the Chamber of Commerce Rooms, Charlotte Square, Edinburgh. Social meetings are also held on the second Thursday of the month in the "Waterloo," and these will continue throughout the summer, although the formal season has just ended. Radio Amateur News, produced by the Club, is circulated throughout the membership, and the first issue ran to 70 copies. (We should also like to see it.- Ed). For Secretary's QTH see panel.

Nottingham Short Wave Club. -This Club meets every Monday, 7.15 p.m., at 23 Gamble Street, Nottingham, but membership is growing and larger premises are being sought. Morse sessions are held at every meeting, and the, annual Field Day event is to be held at the end of May. Three members are sitting for the RAE and hope to be on the air as a result thereof !

Secretary's QTH in panel.

Stoke-on-Trent Amateur Radio Society.-Meetings continue every Thursday at the Taber- nacle Hall, High, Street, Hanley, 7.30 p.m. Recent lectures have been on Speech Amplifiers (G3UD), Con- verters (Mr.J. Roberts), Radio Maths (Mr. Ken Parkes) and - Receivers Through the Ages (G2WN). A Field Day is


organised for May 23, and several members are busy making 5 -watt transmitters. It is hoped to exchange lectures and lecturers with the Leek & District Radio Society.

Spen Valley Radio & Television Society.-Membership and activity are both growing steadily. Lectures and visits to places of interest are a regular feature, and meetings are held at the Temperance Hall, Cleckheaton on Wednes- days at 7.30 p.m. (fortnightly from May 19 onwards).

Merseyside Radio Society & Liverpool & District Short Wave Club.-Both clubs are very active, and publish a joint monthly called Merseyside Amateur Radio Review. From this we learn that an NFD Rehearsal is being run on May 29. Several meetings are on the cards for May, but we have no details of June activities. The M.R.S. Club Station G3DPZ is now licensed for 150 watts, and construction of a suitable QRO outfit is about to begin.

Sutton & Cheam Radio Society. -At the last meeting G2NH, now Vice -President, gave a lecture on 144 me work, and exhibited three converters, a transmitter and a four -element array. The Club's 1'7 me 'phone net, at the other end of the spectrum, is active and successful. New members are welcome on the first and third Tuesdays of the month, at Ye Olde Red Lion, Cheam. New Secretary's QTH in panel.

Bury & District Radio Society. -During April, a Hamfest was held, 83 members and friends attending, and the club transmitter was on the air during the festivities. Several contacts were made, the usual " swindles " were organised, and some films were shown. Meetings are on Thursdays at Hodson's Mill, Tottington (7.30 p.m.) except on the second Thursday. when they are at the Athenæum, Bury.

Medway Amateur Receiving & Transmitting Society.-Recent lectures have covered the subjects of Television Re- ceivers, Frequency Modula-

tion, and Apparatus for NFD. In preparation for the latter, members have constructed a marquee to house the gear and the " sleepers." The contest for the Capt. Plugge Trophy has taken place during May, and it is planned to hold a Hamfest on June 28 at CIub Headquarters.

Worthing Radio Group.-On May 6, Mr. J. B. McMillan, of the EMI Institutes, gave a lecture on the Directive Pro- perties of Short Wave Aerial Systems. This was illustrated by means of equipment which was on show at Radiolympia. There is much activity prior to NFD and Worthing are hoping to repeat their success of last year.

Southend & District Radio Society.-At the May meeting Mr. Peck's lecture on High Speed Electronic Flash Equip- ment took place, and great interest was shown in this subject. The June meeting is booked for Friday, the 18th, when RSGB matters will be discussed. The meeting on July 2 is not yet booked.

Following are the names and addresses of the Secretaries of Clubs whose reports áppear in this issue. They will be pleased to welcome new or prospective members and to give every assistance :

BASINGSTOKE. L. S. Adams, 16 Bramblys Drive, Basingstoke, Hants. BOVINGDON AIRPORT (G3DGS). J. D. Lord, Police Station, Bovingdon, Hemel Hempstead, Herts. BURNHAM AND HIGHBRIDGE. T. N. Carter, G3BPV, P.O. Radio Station, Highbridge, Somerset. BURY (G3BRS). R. H. McVey, 46 Holcombe Avenue, Elton, Bury, Lancs. CHELTENHAM. H. Brislin, 52 Cleevemount Road, Cheltenham, Glos. COVENTRY (G2ASF). J. W. Swinnerton (G2YS), 118 Moor Street, Coventry. EAST SURREY. L. Knight, G5LK, Radiohme, Madeira Walk, Reigate, Surrey. EDGWARE (G3ASR). R. H. Newland, G3VW, 3 Albany Court, Montrose Avenue, Edgware, Middx. KINGSTON. A. W. Knight, G2LP, 132 Elgar Avenue, Tolworth, Surrey. LEEDS. F. W. Kirk, G3ADY, 29 Brookfield Road, Leeds 6. LIVERPOOL (G3AHD). B. G. Meaden, G3BHT, 10 Alfriston Road, West Derby, Liverpool 12. LONDON. N.W. H. E. Hardy, 4 Market Lane, Burnt Oak, Middx. LOTHIANS. J. W. Sime, GM3CVJ, clo Miller, Ettrick Grove, Edinburgh 10. MEDWAY. S. A. Howell, G5FN, 39 Broadway, Gillingham, Kent. MERSEYSIDE (G3DPZ). C. M. Johnstone, 6 Flawn Road, West Derby, Liverpool. NORTH KENT. J. L. Bowes, G4MB, 20 Broomfield Road, Bexleyheath, Kent. NOTTINGHAM. J. Rowbottom, 9 Mansfield Street, Sherwood, Nottingham. READING. L. Watts, G6WO, 817 Oxford Road, Reading, Berks. SOUTHEND (G5QK). J. H. Barrance, M.B.E., G3BUJ, 49 Swanage Road, Southend-on-Sea. SPEN VALLEY. W. C. Longman, 16 Victoria Terrace, Cleckheaton, Yorks. STOKE-ON-TRENT. D. Poole, G3AQW, 13 Oldfield Avenue, Norton -le -Moors, Stoke-on.Trent. STOURBRIDGE. W. A. Higgins, G8GF, 35 John Strict, Brierley Hill, Staffs. SURREY (CROYDON). L. C. Blanchard, 122 St. Andrews Road, Coulsdon, Surrey. SUTTON AND CHEAM. B. J. Blount, 5 Priory Crescent, Cheam, Surrey. THAMES VALLEY. A. Mears, G8SM, Broadfields, East Molesey, Surrey. TORBAY. K. J. Grimes, G3AVF, 3 Clarendon Park, Tor Vale, Torquay. WANSTEAD (G3BRX).' R. J. C. Broadbent, G3AAJ, 24 St. Margarets Road, Wanstead Park, London,

E.12. WEST BROMWICH (G3BWW). W. G. Johnson, G2BJY, 22 Lynton Avenue, West Bromwich. WEST KENT. R. L. Pluck, G4AY, 9 Prospect Road, Southborough, Kent. WEST SOMERSET. T. C. Bryant, G3SB, 29 Lower Park, Minehead. WIRRAL. B. O'Brien, G2AMV, 26 Coombe Road, Irbv, Heswall, Cheshire. WORCESTER. J. Morris Casey, GSJC, c/o Brookhill Farm, Ladywood, Droitwich. WORTHING. G. W. Morton, 42 Southfarm Road, Worthing, Sussex.


Kingston & District Amateur Radio Society.-Their fortnightly meetings continue to be well attended. Fin al arrangements are now beng made for a Field Day on Sunday, June 6 ; the next regular meeting is at the Kings- ton Hotel, June 17, at 7.30 p.m.

London Transmitting Society. -The next meetings will be on June 2, July 7 and August 4, all at 8 p.m. at the Stag House Civic Restaurant, Broadway, Burnt Oak, Middx.

Wanstead & Woodford Radio Society.-The main event since last issue was the May -Day Fete at Wanstead House. The society had- two transmitters on the air, G3BRX on 1 7 me and G2BRR/P on 7 me ; both had many contacts and the public showed great interest. The Secretary would like to hear from other clubs who meet at local Community Association HQ's, with a view to making contacts on the air.

Edgware & District Radio Society.-Recent events have included two film shows-one a talkie on Radar and other subjects, and the other a silent showing of NFD and D -F Contest films. When no lecture has been arranged, this Club has tried splitting members up into discussion groups, and this scheme has been so successful that it will be carried out on all " free " evenings in future.

Burnham & Highbridge Ama- teur Radio Society.-This Club is now firmly established with over thirty members. Recent lectures were on Aerials (G3CPV) and An Unconventional CO -PA Transmitter (G8PG), and a successful junk sale was also held. Plans for the club transmitter are afoot and some talks on Radar are also being arranged.

West Bromwich & District Radio Society.-A full programme of talks and lectures has been arranged to cover the next six months, and the Club continues its fortnightly meetings. These are held on alternate Mondays at Charle - mont Schools, 7.30 p.m.- new members will be welcomed.

Taken at the April meeting of the Burton Radio Society, G2R11 (chairman) points out certain features of his oscilloscope. Among those to be seen in the photograph are : Standing, left to right ; G3BSL, G3AFS, G3ACR (the Burton QRP king), G3BBM and G2AQV ; G3CYL is seated, right, and the

lady is second operator at G3BSL.

West Somerset Radio Society. -The first meeting of this newly -formed club took place on May 7. Interest covers amateur transmission, HF, VHF and television reception, and high -quality reproduction as well as radio control of models. All interested persons in the locality are asked to contact the Hon. Secretary at the QTH shown in the panel.

Cheltenham.-A talk was recently given by G3AKZ on " Noises from the Sun," illustrated by slides and an epidiascope. G3ACT lectured on Radar as applied to Anti - Aircraft Work. It is hoped to run a film show shortly ;

meanwhile, the slow Morse transmissions are going strong and a 20 -metre beam is nearly ready for NFD.

Leeds & District Amateur Radio Society.

An item of sad news from Leeds this month mourns the loss of the society's past Chairman and Secretary, Mr. S. Chester, who died suddenly on May 2. He was an old stager in the radio world and had been held in high esteem from the Club's teething days; his loss will be keenly felt.

Worcester & District Amateur Radio`e Club.-MD5AF and several members of the Mal- vern Radio -Society visited this club for the May meeting, and it is hoped that closer co- operation between the two societies will result. Worcester are paying a return visit in the near future. A lecture with film illustrations on " Valves " will be given at the next meeting, on June 3.

Coventry Amateur Radio Society.-Readers will know by now that G6WX, President of the CARS, has been elected Mayor of Coventry. He has also acquired a lesser dis- tinction in the shape of his DXCC Certificate for 100 post-war countries on 'Phone. At a recent meeting Mr. T. R. Theakston, B.Sc., lectured on " Mathematics-How and Why." This talk, which was an outstanding success, was followed by a demonstration of High Quality Sound Repro- duction by Messrs. Gardner and Orange.

Torbay Amateur Radio Society. -During May 24 members went on an " outing," the main purpose of which was to visit G5BY at Bolt Tail. G2DYM's " shack " was also visited on the return journey.

D


The club will be delighted to welcome any amateurs visiting the district for their summer holidays, and meets on the third Saturday of the month at the YMCA, Torquay, 7.30 p.m.

Wirral Amateur Radio Society. -Activity continues at a high level, many members being busy with NFD preparations. June meetings are booked for the 9th and 23rd, both at the YMCA, Whetstone Lane, Birkenhead. Recent lectures have been on Carrier Tele- phony, by G3DLF, and Aerial Coupling, by G3AKW.

Bovingdon Airport Club.-The club transmitters are now on the air, and some interesting contacts have been made with 3 or 4 watts on the Top Band. A high spot was a visit to the

GEC Research Department at Wembley. Bovingdon extends a welcome to other clubs to visit them ; a conducted tour of the Airport will be arranged, including examination of all the modern radio equipment. Best time is a Saturday after- noon, and the Secretary will be pleased to discuss and make all arrangements.

Surrey Radio Contact Club (Croydon).-Those who attended the May meeting were treated to a very interesting talk on Practical Work on the 12 -cm Band. Messrs. P. Bradsell and K. W. Drum- mond, who gave it, are both members of the recently - formed South London Micro - Wave Group. Next meeting is on June 8, Blacksmiths Arms, Croydon, at 7.30 p.m.

East Surrey Radio Club.- This club meets on the fourth Thursday of the month, and thus our reports are always somewhat out of date. At the April meeting, on the 22nd, two excellent sound films on General Electronics, loaned by the BTH Company, were shown, and received with great interest. New members will be heartily welcomed.

West Kent Radio Society.- First report from this newcomer, catering for amateur activity in the Sevenoaks and Tonbridge area. Premises have been obtained at Cul- verden House, Tunbridge Wells, and talks have been given by G3BGU on Trans- mitter Design, and by G2UJ on The 144 me Band. An NFD station will be operated by the club at Southborough.

THE AT CODE

Since we started talking about this, more comment has come in, including some votes in support from operators who said that at first they thought the Code was hardly worth introducing in face of the existing Q Code.

G3XT, originator of the AT Code, writes as follows : " An encouraging point is the absence of any valid criticism ;

the only criticisms that have been forthcoming so far will not bear examination. For instance, the suggestion that the Q Code covers all amateur needs is obviously incorrect, as there are no Q equivalents to the ATC abbreviations ATD, ATE, ATG, ATI, ATO, ATP, ATT, ATU and ATW. The criticism that the 'AT Code is an unnecessary complication' does not seem very convincing either, when one realises that even a beginner can learn it in a few minutes ; moreover, being a self-evident code, one can actually guess correctly at most of the meanings. If the AT Code had by chance appeared before the Q Code, no amateur would have bothered with the latter, any more than he does with that other commercial abbreviation system, the Z Code. The idea that the AT Code might not catch on with foreign stations is also unfounded. At a meeting of 200 members of V.E.R.O.N., the majority of the PA's present were in favour-though her; again it was the old-timers who were against a change. The AT Code has also been reprinted in the German amateur paper QRV."

Thus G3XT, and the points he makes are sound. The main -difficulty, and probably the only one, is the natural reluctance of many operators to change their habits, though it is not at all improbable that if people who like the AT Code would use it, in time it might become universally accepted.

In the meantime, we invite Editors of overseas Amateur Radio publications to reprint the original article on the AT Code, which appeared in the Short Wave Magazine for February, 1948, and to ask their readers' opinions on it.

ORDER ON US

If you have difficulty in getting the Short Wave Magazine regularly and on time a direct subscription order on us will guarantee its despatch to you by post on the day of publication-the first Wednesday in the month. The cost is 20s. for twelve issues and the address for your order The Circulation Manager, Short Wave Magazine, Ltd., 49 Victoria Street, London, S.W.I.

* BLACK CRACKLE FINISH

We have had a number of enquiries as to a source of supply for black crackle paint. We are informed that it can be obtained from Gedge & Co., Ltd., 88 St. John Street, Clerkenwell, London, E.C.1.

VOLUME VI

Short Wave Amateur Band

Frequency in Mc/s

7.0

14.0

28.0

585

Length in feet

32.75

16.5

8.0

4.0

SHORT WAVE MAGAZINE 275

THE IDEAL TRANSMITTING AND RECEIVING AERIAL FOR THE AMATEUR This very practical kit consists of a "T" strain insulator, 80 ft. of cadmium copper wire and 80 ft. of L336 balanced twin feeder with plug and socket to suit (see illustration below) and two glass end insulators. The "T" insulator in the illustration on which sensible terminals and "cable grips" are provided, has been designed to take the feed from the centre of a half -wave di -pole. For receiving purposes, the length per half -section is not critical to within a few inches, but for transmission the lengths given are approximate only and must be slightly re -adjusted to the correct length from the formula :-

224

Short Wave Broadcast Band

Frequency in Mc/s

6.0 9-0

12.0 15.0 18.0 21.0

Length given is per half -section

Length in feet

40 27 20 16

13 I

BELLING & LEE LTD' CAMBRIDGE ARTERIAL ROAD, ENFIELD, MIDDX-

Length of half -section in feet Frequency in Mc/s Cadmium copper is supplied as this will not stretch-

a most important matter if the aerial is being used for transmission. Suitable for 200 watts RF up to 28 me/s. The complete kit L609. PRICE 35/9. The "T"strain insulator L333 supplied separately. Price each 3/3, also L336 Balanced twin feeder at 74d. per yard.

HEADPHONES WHICH UPHOLD BRITISH PRESTIGE

The S. G. Brown Type " K " Moving Coil headphones supply that High Fidelity Reproduction demanded for DX work, monitoring and laboratory purposes, etc.

OUTSTANDING CHARACTERISTICS

D.C. RESISTANCE, 47 Ohms. IMPEDANCE, 52 Ohms at 1,000 c.p.s. SENSITIVITY, I.2x I0-38 watts at

I kc. = 0002 Dyne/cm=,

Price L 5 : 5 : 0 Per Pair

Your local dealer can supply

Descriptive Literature on request

HEADPHONES WHICH UPHOLD BRITISH PRESTIGE

TYPE "K" For details of other S.G. Brown Headphones

4 (prices from 30/-to63/-)writeforillustrated J Brochure "S.W."

VICTORIA RD., NORTH ACTON, LONDON, W.3.

n Phone : ACOrn 5021


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OUR NEW LIST IS NOW AVAILABLE. All enquiries must be accompanied by a 2fd. stamp. ALUMINIUM CHASSIS. Substantially made of bright aluminium, with four sides, 10 in. x 8 in. x 24 in., 7/- ; 12 M. x 9 in. x 24 in., 7/9 ; 16 M. x 8 M. x 24 in., 8/6 ; 20 in. x 8 in. x 2} in., 10/6 ;

22 in. x 10 in. X 24 in., 13/6. OSCILLOGRAPH POWER UNIT KITS. Input 230v.- 50c. include transformer, metal rectifiers, voltage doubling and smoothing condensers. Type 409, output 900 v. 25/-. Type 310, output 1,800v., 30/-. SPECIAL HEADPHONE OFFER. High-grade Double Headphones, using balanced armature units. D.C. Res. 60 ohms. 3/6 per pair. Matching Transformer if required, 2/6 each. OSCILLOGRAPH FOUNDATION KIT. Com prises a transformer giving an output of 800v., condensers, metal rectifiers, 3f -in. Cathode Ray Tube and base, and L.T. Transformer. Price 55/- H.T. ELIMINATOR AND TRICKLE CHARGER KIT. Consists of a complete kit of parts to con- struct an H.T. Eliminator with an output of 120v. at 20 m/a and provision for Trickle Charging a 2v. Accumulator. Two Metal Rectifiers are employed. With circuit, 35/-. NEW 2 -VALVE SHORT WAVE KIT. 16 to 2,000 metres, Switched Coil Pack ready wired and tested. 2 Mazda HL23 Valves, 'Phones, H.T. and L.T. Batteries, Condensers, resistors, diagrams and steel case, all ready to assemble. £3/19/6 COLLARO ELECTRIC GRAMOPHONE MOTORS with 12 -in, turntable. A.C. only. 100-250v., £5/18/4. COLLARO ELECTRIC UNIT with Magnetic Pick-up and Auto Stop. A.C. only, 100-250v., £9/13/6. DITTO UNIT with Crystal Pick-up. A.C. only, 100-250v., £11/2/2. CONRAD RIM DRIVEN ELECTRIC GRAMO- PHONE MOTORS with 9 -in. Turntable. Fixed Speed (78 r.p.m.) for 200-250v. A.C. only, £4/19/3.

C.R. TUBES, VCR97, 6 -in, diameter, green screen, 4v. la. Heater, 2,500v. max. H.T. Com- plete with socket, in maker's original cartons, 55/-. MULLARD M.W,18-2 TELEVISION TUBES. 7 -in. diameter. 2v. Heater. 5kV max, H.T. Mazda Octal Base, £5/19/6, in maker's cartons. C.R. TUBES. We have available a large quantity of E.M.I.4/1 Cathode Ray Tubes, 31 -in. diameter, green screen, short persistence, 4v. 1 .3a. Heater 800v. H.T. Complete with socket, 17/6 each. C.R. TUBES. V.C.R.138 (equivalent to E.C.R.35), 3f -in. diameter, green screen, 4v. la. Heater. 1,200v. H.T. Complete with socket and Mumetal Screen, 39/6 each.

R107. ONE OF THE ARMY'S FINEST COM- MUNICATIONS RECEIVERS. (See " W.W.", August, 1945). 9 valves, R.F. amp. osc. Frequency Changer, 2 I.F.'s (465 kc), 2nd Detector, AVC. Af. amp. A.C. mains, 100-250v. or 12v. accum. Frequency range 17.5 to 7 me/s., 725 mc/s to 2.9 mc/s, 3 to 1 2 mc/s. Monitor L.S. built in. Complete. Write for full details. £16/16/-. Carriage paid.

COLLARO AUTO CHANGERS with Magnetic Pick-up. A.C. only, 100-250v., £22/4/4.

SPECIAL VALVE OFFER

1A7, 1135, 1N5, 3Q5, 9/6 each, 16/- Set.

6F6 6V6 CV6 VR65 VR92 VR56

(8541, 6.3 v.) (EA50)

(EF36)

10/6 8/6 6/- 5/- 5/- 6/-

VU134 VU39 VR137 VR136 VS70 VT60A

(HVR2) 10/- (R3) 9/- (E052) 5/- (EF54) 7/6 (7475) 7/6 (807 Ceramic) 10/-

VR78 (D1) 2l6 717A - i,R

VR55 (EB033) 5/- 125137 7/6 VT86 (6K7 met) 10/6 12SL7 10/- VR503 (KT33C) 10/- 12A6 7//6

VR57 954

(EK32) 7/6 5/-

VR91 RL18 5Z4

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7/6 6138 - 5/- 6K8 0/6 6B7 - 5/- 1S5 5/ -

MAINS TRANSFORMERS at exceptional prices. All are heavy duty and robust. All 230v. 50 cycles input.

Price 3 500-0-500 v. 150 m/a. 4 v. 21a. 4 v. 5 a.

4 v. 1 a. 4 865-0-865 v. 500 m/a. Tapped at 690 v.

and 760 v. 4 v. 3 a. 35 300-0-300 v. 250 m/a. 4 v. 3 5 a. 6 3 v.

5-7 a. 6-3 v. 1-2 a. 31 40 v. 3 a. and 104 v. 1 5 a. (auto-

wound) 32 700-0-700 v. 150 m/a. and 1000 v.

30 m/a. 4 v. 1 a. 4 v. 4 a. .

33 38v. at2a. tappedat36v.34v.32v. 34 1500-0-1500 v. 120 m/a. 4 v. 2-3 a.

4 v. 2-3 a.49 275-0-275 v, 120 m/a. 5.v. 2 a. 69 v.

25 a. 6.3 v. -3 a. ct... . .. 42 500-0-500 v. 170 m/a. 4 v. 4 a. . .

43 4 v. 20 a. 46 100 watt auto 230 v. 1513.v. 100 v. 50 v.

35)-

75/-

35/-

21/-

40/- 15/-

55/-

29/- 35/- 25/- 12/6


fa 7NFjÿ pLDERF

. tells you all about the complete range of Henley SOLON Electric Soldering Irons, for the standard voltage ranges of 200/220 and 230/250: 65 watt and 125 watt models fitted with oval -tapered bits or pencil bits and 240 watt models fitted with oval -tapered bits are available.

Write to -day for the new folder ref. Y.10 describing

W. T. HENLEY'S TELEGRAPH WORKS CO. LTD.

(Engineering Dept.) 51-53 Hatton Garden, London, E.C.1

VALVES, RX. 6J7, 6517, 6K7, 6SK7, 6SH7, 6AC7, 6SC7, 6SR7, 6Y6, 6J5, 6C5, 7/6 ; 6V6, 8/-; 6L7, 6K8, 6N7, 6SN7, 1613, 10/- ; 6L6G or MET, 12/6.

RECTIFIERS. 6X5, 5W4, 7/6 ; 5U4, 5Z3, 10/- ;

836, 20/- ; 5R4GY, 950-0-950 175 mills., 7/6.

VOL. REG. VRI05, 7/6 ; VRI50, 8/-.

TX. VALVES. 807, 12/6 ; 81 1, 45/- ; 814, 45/- ;

813, 70/- ; 100TH, 60/- ; 1-IK257B, 60/-.

TUSB, TU7B, 25/-.

METERS. M/C Weston, Ferranti, Met. Vic., 24" round flush, 0-50 mills. 0-200 mills., 10/6 ;

0-1 Weston, I6/- ; 0-150 Ferranti 2" square flush, 7/6.

U.S.A. TEST METERS. M/c 1,000 ohms per volt. D.C., 0-30v, 0-400v, 0-1,500v, 0-150 mills., A.C., 0-I5v, 0-150v, ohms 0.3,000, 0.300,000. By 8 -way rotary switch. Complete with test prods by Triumph, Chicago, £4.

BLEEDERS. 15K, 35K, 40w, I/-. VALVE HOLDERS. Ceramic, octal, 1/-, 4 -pin UX, 1/-, Loctal, 6d., Spring Loading.

CON. VAR. Tx 1,000v cer. ins. 100pf, 2/6 ;

100 + 100, 5/- ; 140pf 1,500v, 6/- ; 50 + 50, 8/-. CON. VAR. RX. 50pf, 1/9 ; 100pf, 1/9 ;

75 + 75, 3/- ; 0003, 3 -Gang, 7/6. 1155 S.M. Drive, 4/- ; National Velvet Vernier, 8/-. BC348. £17/10/-. TX. UHF. AM33ART, 2, HK257B in P.P. 2,836, Rec. Power Supply 400 cy., but very easily adapted for normal working by new power supply. I kW RF, brand new. £10 in original boxes.

THE A FIVER (see QST Jan.). BC453B. Brand new with 6 valves. Will improve even an AR88. Band width 6-5 kc at 1,000 times down, £3. BC454 and 455. £2 to clear. BUTTON BASE. 1T4, 155, IRS, IL4, IA3, 354, 3A5, 6AG5 at 7/6 each. RADIO COMPASS UNITS. Bendix BC433, complete, new, boxed, 15, 6.3 valves £5/10/-. MAGSLIP. AC motor and Slave, 25/- pair.

XTALS. 7 me to 7,300 kc, sealed with holder. Yr. freq., 12/6 ; 28 me Band, 30/- ; 1,000 kc Octal, 30/-.

EVERY ITEM OFFERED BRAND NEW IN ORIGINAL PACKING POST PAID BY RETURN

H. WHITAKER G3SJ 10 YORKSHIRE STREET, BURNLEY Phone : 4924


CANNY CONSTRUCTION

Delivery by return of above sizes.

BUT NOT TIN -CANNY The studied design of the F B chassis ensures the utmost rigidity and convenience because it was developed by Radio Engineers for Radio Engineers

AND at a price to suit the pocket of every radio amateur.

PERSONAL SERVICE. Send us details of your chassis problems. Our designer is at your service.

17" x 10" x 22" 9/-. 10" X 8f" x 2z" 6/6. 8r x 5" x 22" 5/-.

Post and packing 1/- extra Panel Brackets 1/3 pair

Chassis punched to your template at small extra cost

Other sizes, prices in proportion, delivery 2 to 3 days.

FB PRODUCTS 4BRADFORDLE S

YORKS

SAMSONS SURPLUS STORES ANOTHER DELIVERY OF R.C.A. MASTER OSCILLATORS Frequency range 0 -IO me/s. Output sufficient to drive any P.A. Uses 807 valve in extremely stable circuit. Very accurate dial calibrations with unique dial mechanism. Metering of doubler or buffer stages grid current included. Housed in solid cast case with shock absorber mountings. Supplied brand new with accessories and operating manual. As from makers. £6/101-. Carriage 5/, No C.O.D.

R.C.A MAINS TRANSFORMERS. Primary 190-250v. A.C. Secondary 2,000-0-2,000v. or 1,500-0-1,500v. I.75kVA. Price f6/I0/-, plus 7/6 carriage. No C.O.D.

HOWARD BUTLER METERS, 0-150v. D.C. i per cent. Accuracy ; 5; in. scale mounted in fine bakelite case, 6+ in. x 6; in. x 3 in. Brand new, 52/6. Carriage paid.

POWER UNIT 584. 80v., 2,000c., but represent wonderful component value. Complete with 2 VU508 high voltage condensers, resistors, etc. Built in crackle finish metal case, 17 in. s 9 in. x 9 in. Brand. new, 27/6, plus 2/6 carriage. No C.O.D.

0-500 MICROAMPMETERS. Brand new. 2 in. scale. By leading makers. 10/6. Post 6d.

STILL AVAILABLE M.C.R.I. Communication receivers. Complete in every respect with'phones, aerial, earth, batteries and power pack to work on 90v.-250 AC or DC. Frequency range 20-3,000 metres. Brand new sealed in maker's canisters. 611/10/-. Carriage paid. No C.O.D.

12 VOLT VIBRATOR PACKS. Output 210v. DC 70 mA. Input 12v. DC. Completely smoothed and rectified. Brand new, 21/-. Post,l/-.

MUIRHEAD SLOW MOTION DIALS Without flange. Brand new and boxed. Calibrated at 0-180 deg. Price 8/6. Post 6d.

169-171 EDGWARE ROAD, LONDON, W.2 Tel. : PAD 7851

I25 TOTTENHAM CT. RD., LONDON, W. Tel.: EUS 4982

All orders and enquiries to our Edgware Road branch, please.


THE TRADING POST - G8V6è HOME CONSTRUCTED SOUND AND TELEVISION RECEIVER FOR £23 (carriage and packing included). Made up from X.A.M. Radar Equipment. Complete circuit, diagram and instructions. Sound and vision units and complete list of additional components to complete sound and vision receiver. Any item sold separately. Send for List. POWER SUPPLY for the R.1155. Complete with amplifying stage, only requiring a loud speaker. Input 200/250v, 50 cycles. In grey crackle case, with leads and Jones plug. £4/I5/ - POWER UNITS, Input 200/250 v. 50 cycles. Output 200 volts at 60 mA. D.C., filtered and smoothed and 63 volts, 3 amps A.C. Suitable for any receiver etc. £3. Ex-R.A.F. 27 ft. sectional steel masts. These are cigar -shaped masts of exceptional strength, being approx. 3" at top and bottom and 5" in the centre. Rope guys are included, and the mast packs into approx. 9 ft. for transport. Ideal for rotary arrays. £3. A number of IFF sets still available at E1/12/- each. Wireless remote control units (Canadian), £l/5/-. We have a very good line in partly stripped power unit cases, which still contain the following useful articles :-13 fixed resistors, I variable resistor, 14 condensers, including 3 high voltage, 3 L.F. chokes, 8 valve holders, all mounted on a very accessible chassis, and the whole sliding into a

well made, and well ventilated cover. This bargain cannot be repeated when stocks are exhausted. This unit measures 12" x 8z" x 7z". A gift at 7/6, plus 2/6 postage. Send for General Lists.

THE TRADING POST 40 SOUTH EALING ROAD, W.5

Phone : EAL 5903

EXPORT DISPOSALS CO. A DIVISION OF MAIL ORDER SUPPLY CO.

Formed for the benefit of overseas readers, including trade organisations, to whom we can offer the benefit of bargain -priced radio, electrical and allied equipment.

Note.-All U.K. readers may order from this advertisement.

MINIATURE METERS. All new and cartoned 0-1ma. Moving coil D.C., 25" round flush mtg., black .. 15/11 0-5ma. Moving coil D.C., 2" sq. flush mtg., black .. 5/- 0-30ma. Moving coil D.C., 25" round flush mtg., black .. 6/9 0-40/120ma. Moving coil D.C., 2" round projecting, black 7/- 0.50ma. Moving coil D.C., 2" & 20" round projecting, black 7/3 0-100ma. Moving coil D.C., 3" rectangular portable, black,

with circuit shorting switch 12/6 0-150ma. Moving coil D.C., 2" square flush mtg., black.. 7/6 0-500ma. Moving coil D.C., 2" & 25" round projecting, black 6/- 0-.5amp R.F. Thermocouple, 2" sq. flush mtg., black.. 5/- 0-2.5amp R.F. Thermocouple, 2" round projecting, black 7/3 0-3amp R.F. Themocouple, 2" sq. flush mtg., black .. 616 0 -damp R.F. Themocouple, 2" sq. flush mtg., black .. 6/6 10-0-20amp Moving coil D.C., 2" round flush mtg. .. 516 0-20amp Moving coil D.C., 2" round projecting, black 5/6 20-0-100amp Moving coil D.C., 2" round flush mtg., black 5/6 5-25amp Moving iron, 20" round, flush mtg., black .. 716 5-40amp Moving iron, 21" round projecting, black .. 6/8 50-0-50amp Moving coil D.C., 2" sq., flush mtg., black 5/- 350-0-350 millivolt Moving coil D.C., 25" rnd f 1. mtg., black 15/- 0-10v Moving coil D.C., 2" round projecting, black .. 8/6 0.3áv 0.70 amp dual Moving coil D.C., 2" sq. fl. mtg., black 9/- 0-300v Moving coil D.C., 2" sq. flush mtg., black .. .. 5/6 0-1,500v Electrostatic, 21" round projecting, black .. 20/- 0.2,000v Electrostatic, 21" round flush mtg., black .. 22/6 0-3,500v Moving coil D.C., 35" projecting, black.. 151- 0-0,000v Moving coil D.C., 30" round projecting, black.. 27/6

TERMS Cash with Order. For overseas add sufficient freight and packing to cover requirements, at rate of 3/6 per £1. For the U.K. add 2/- per £1.

3 Roberts St., Hampstead Rd., London, N.W.1 Callers-to 24 New Road, London, E.1

Stepney Green 2760-3906

G6HP Absorption Wavemeter 'Phone Monitor. Bandswitching, including thermo meter 0-200 Mills and Westector. £5.

THE MAIN AMATEUR SERVICE OF THE NORTH Ex W.D. C.R. Indicator Unit less C.R. Tube.

Steel case 6;" wide, 8+" high 12" deep.

Hinged glass window, remov- able cover and bottom plate. Welded 34" deep chassis.

Contains C.R.Tubeholder,one main hole only through chassis. Tag strips, resistors, condensers, potentiometers. 2 heavy duty 4 way keyed sockets. (Plugs available at 2/6 each.)

An ideal Foundationfºran Oscilloscope. Offered at 1.3/- 2ee" or 3" C.R. Tubes at 50/- each.

each plus 1/6 Postage.

Complete Kit of parts including mains supply with circuit for building the G6HP Oscilloscope for Wave envelope or Trapezoidal pattern examination at £6 inclusive. Oscilloscope built and tested with full instructions at Et/IO.

Amateur Radio Service G6HP,

Canning Street, Burnley, Lancs. Telephone 2999


TWO SPECIAL OFFERS BEAMS AND MASTS

I am offering, this month only, a complete kit of

Duralumin tube for Elements and Boom, with cast Aluminium head to make a very efficient

10 METRE THREE -ELEMENT BEAM. COMPLETE

DETAILED INSTRUCTIONS SUPPLIED FOR

ASSEMBLY AND OPERATION.

You have only to drill a few holes, find two nuts

and bolts, to complete the Beam array.

BEAMS ARE POPULAR BECAUSE THEY PUT

THE SIGNAL WHERE YOU WANT IT, ALSO

GIVING YOU THREE TIMES INCREASE IN SIGNAL STRENGTH OVER A DIPOLE AERIAL.

ONLY 59/6 GET A BEAM UP DURING THE SUMMER MONTHS

THE IDEAL MAST EXTREMELY LIGHT, YET SUPER STRONG FOR

ANY EXPOSED LOCATION, LOOKS NEAT

WHEN ERECTED. I can supply three lengths of Duralumin tube with insert sleeves to make the

IDEAL MAST 30/32 ft high.

You have only a few holes to drill, then bolt sections together, some wire for guys to complete.

ONLY WEIGHS II lbs, YOU CAN ERECT IT

WITHOUT HELP.

ONLY 57/6 (Two for £5/101-)

DO NOT DELAY -ONLY A VERY LIMITED NUMBER

HERBERT TEE (G8DC) 469 HIGHER BRUNSHAW, BURNLEY, LANCS (Owing to pressure of business, no callers at present, please. All Mail Orders)

COMMUNICATION RECEIVERS -THE BUY OF THE MONTH By Collins, Hazeltine, Air King, etc., to

Collins' rigid specification 7 Tube communication receivers I.5-12 me in 3

Bands. Line up, RF, Mixer, Osc., 2 IF's 2nd det. AVC BFO, pentode audio first class lob all ceramic switches, valve holders, gang condenser and coil forms. RF and audio gain controls BFO control phones and speaker output, diecast chassis, unit constructed, frequency calibrated dial, 25-1 S.M. drive, logging scale, etc., easy to get at.

Full circuit diagram with each receiver dead stable and excellent performance.

Size 14" L x 10" H x IO" D weight 43 -lbs. all in excellent condition in black crackle case.

Power requirements 12v model 12v -I amp) H.T. 6v model 6.3v-2.5 amp) 250v

80ma 3 prices 12v model 66/10/0

6v model £7/10/0

Without tubes £410/0

Packing case 30/- refundable. If you doubt the value offered write for photographs of this excellent equipment. S.A.E. please.

Noise Limiters No need to make any alteration to your receiver, lust plug in, 100 only. Full dope supplied. 7/6

Wire or W CHAS. your Requirements to

a

CHAS, H

Moving Coil Microphones Genuine G.E.C. me mikes in streamline case few only 62/10/0 each.

For Mobile Use We can offer a limited number of double motor generator units fully smoothed, two separate machines made for the above receivers and a portable T.X. 400v 200 mA supply, with starting relays by the best American makers, only £2110/0 each.

Alao we can offer 12v Vibrator packs by Mallory fully smoothed suitable for above (output 300v 100 mA) at 29/6.

Bargains in Valves from Stock TZ40's, 30/-, 6AG5 (400 me pen.) 12/6, 6C4 (VHF triode) 11/-, 6N7 metal II/-, 616 (500 me dual triode) 15/- , 6F6 9/-, KT66's 10/6, GU50's I5/-, DH63 8/6, U52 I0/-. ALL BRAND NEW IN MAKERS' CARTONS. FEW only unboxed but brand new 813's with ceramic holder f2/I0/0 each.

AR88 D and AR88 L.F. Instruction books. If you are interested in these please drop us a line.

Communication Receivers best selection of reconditioned receivers in the Midlands. RCA, RME, National, etc., write for a list.

YOUNG G2AK 880 Washwood Heath Road, Birmingham 8. STECHFORD 2809


Bargains in

GOVERNMENT SURPLUS

1155 RECEIVERS fitted with output stage Power packs

£10 extra £2/10 carriage £I

U LTRASCO P ES Standard 6" Oscilloscopes £10

carriage I0/- 1FF UNITS Types R3090 and R3121, complete with 13 valves and motor generator 15/ -

carriage 2/6

I125A and I125B RECEIVERS 2 -valve, UHF RECEIVERS, in original

cartons 15/ - carriage free

RF UNITS, TYPES 24-25-27 Type 24 5 preset positions 12/6 Type 27 tuneable 30/ -

carriage free

DISPLAY UNITS Various types and many other bargains.

Send stamp for catalogue to

RADIO EXCHANGE 9 Cauldwell St., Bedford

W. B. RADIO (G4PF)

Limited Number only

BC348 Rx's ... £ 16/10/0

Modified, Complete with Speaker ... ... ... £25/l0/0

TU5B, modified as per QST, into VFO, Complete with valves ... £5/10/0

22d. S.A.E. for Price List

Desk Stand Mike ... (post free) 12/6

RAYMART, EDDYSTONE AND WODEN STOCKIST

45 PRIORY RD., ANFIELD,

LIVERPOOL 4

INFRA -RED IMAGE CONVERTER TUBE

INFRA -RED SENSITIVE I AVER.

VIEWING WINDOW

3 Electron

This is a highly sensitive photocell which, in addition to ordinary ray control operations, can be used for the direct conversion of infra -red into visible light. Price. 14/6, post and insurance 1/6 extra. Send S.A.E. for explanatory leaflet.

W. D. SALES House, Windmill Hill

Ruislip Manor, Mdx.

SMALL ADVERTISEMENTS TRADE ADVERTISEMENTS

9d. per word, minimum charge 12/-. No series discount : all charges payable with order. Insertions of radio interest only accepted. Add 25% for Bold lace (Heavy Type). Press day July issue, June 14. No responsibility

accepted for errors.

OPPER wires. Enamelled, tinned, Litz, cotton, silk covered. All gauges. B.A. screws, nuts,

washers, soldering tags, eyelets. Ebonite and laminated Bakelite panels, tubes, coil formers. Tufnol rod. Flexes, permanent detectors, headphdnes, etc. List S.A.E. Trade supplied.-Post Radio Supplies, 33 Bourne Gardens, London, E.4.

WE HAVE THE LARGEST STOCK OF ENGLISH AND AMERICAN RADIO BOOKS IN THE

COUNTRY, INCLUDING MANY NOW OUT OF PRINT. Write or call for List, Modern Book Co., 19/23 Praed Street (Dept V), London, W.2. Pad 4185.

COMPLETE correspondence course covering Ama- teur and C. and G.I. Examinations, consisting of

12 Lessons. Students trained for Certificates of the City and Guilds of London Institute. Send for particulars.-Orthic-Modern Institute, 72 St. Stephens House, Westminster, S.W.1.

DESIGN, DEVELOPMENT AND CONSTRUC- TION OF APPARATUS OF ALL TYPES;

CALIBRATION SERVICE ; HIGHEST QUALITY WORKMANSHIP ; REASONABLE CHARGES ;

SATISFACTION GUARANTEED.-S. G. BUTTON (G5JY), 81 WOODBRIDGE ROAD, GUILDFORD, SURREY. Q S T CARDS. Distinctive and attractive designs.

Samples and prices from G5KT, 33 Howard Road, Bristol, 6.

CARDS AND LOG BOOKS. APPROVED G.P.O. SAMPLES FREE. ATKINSON

BROS., PRINTERS, ELLAND, YORKS. WANTED HRO, AR88, B2 RECEIVERS. Must be

Ty in first-class condition, appearance and working order. Top prices paid ; particulars Valiance's, 144 Briggate, Leeds, 1.

A TTENTION. DENCO COMMUNICATIONS II -RECEIVER SHORTLY AVAILABLE. A REAL STEP FORWARD IN SHORT WAVE TECHNIQUE. YOU SIMPLY MUST HAVE THE DATA SHEET OF THIS FINE INSTRUMENT. DENCO COM- PONENTS ALWAYS AVAILABLE. ILLUSTRATED CATALOGUE PRICE NINEPENCE. S.A.E. NOW TO MASON'S (S.W.). WIVENHOE, NR. COL- CHESTER, ESSEX.

QUANTITY Ex-A.M. Westectors, WX 6 and WX 12, new and unused. Offers.-J. Walker, 81 Long

Lane, Broughty Ferry, Dundee. QUANTITY 5R4GY rectifiers 950 volt at 175 mills.

7/6 each, 2 for 12/-, 4 for £1. Post free.-Holt 4, Greystoke Avenue, Sale, Cheshire.

QSL


SHORT WAVE (HU«)RADIO G5GX

BEAM POSITION INDICATORS We have pleasure in announcing a large

purchase of remotely -controlled, 360 degree Electronic Beam Indicator Units.

Briefly the unit comprises :- I. The Transmitter Head, consisting of a

360 degree potentiometer in a waterproof housing, with extended spindle suitable for the fitting of pulley or sprocket. Height 8s" x 4k" wide including fixing plate.

2. The Indicator Unit, consisting of a fractional horse-power motor housed in an attractive flush - fitting bakelite case, 4". diameter, suitable for panel mounting. Complete with dead beat pointer.

Power requirements 4-9 volts D.C., 100 mA approximately.

PRICE complete with transmitter head, Indi- cator Unit and wiring diagram ... ... 20, - Packing and postage ... ... ... ... I/ -

No Beam user can afford to be without one. Available only from :- SHORT WAVE (HULL) RADIO

30/32 Prince's Avenue, HULL

Telephone 7168

Selections from our Catalogue LOUDSPEAKERS Goodmans 34" P.M. 2 ohm. ...

Goodmans 5" P.M. 2 ohm. Goodmans 5" P.M. with transformer ...

Grampian 9" P.M. 2 ohm. Grampian 9" P.M. 15 ohm. ...

Rola 10" P.M. 2 ohm. ...

30/- 21 /- 25/-f2

f2

32/ -

TRANSFORMERS 1.F. 465 kc/s 20/- per pr. I.F. 125 kc/s 21 /- per pr.

WIRES & CABLES Microphone Cable, heavy duty, twin screened, 2/6 yard ; Coaxial 80w heavy duty, 1/3 yard ;

Line Cord, 0.3 amp 180 ohms. 2/6 yard; Aerial Wire, 12 S.W.G. enamelled, 75 -ft., 9/-, 140 -ft., 16 /-.

Coaxial Plugs and Sockets. Belling -Lee Chassis type, 3/, Voltage Regulators. VR75/30, VR105/30, VRI50/30, 12/6 each.

(Please include postage on above items)

Send for fully detailed catalogue to A.C.S. RADIO

44 WIDMORE R4 BROMLEY, KÉÑ' :Phoìs RAYPn rtrur'í 0/56

SMALL ADVERTISEMENTS TRADE-continued. SUPER quality American Xtal Oscillators complete

with all connecting leads, plugs, meter, 807 valve, etc., range 1.7 me to 7.5 me ; only requires xtal and power supply, 300-350 volts, 6.3 volts, and you have a 10 -watt transmitter ready to go on the air or a driver unit for the ORO PA. Brand new in wooden packing cases complete with instruction book and one spare 807. Only £4/10/-. For the Ham who wants only the best Brand new R.C.A. Transformers, primary 190- 250 volts 50 C. Secondary 2300-1750-0-1750-2300 volts (nominal output 2000 and 1500 volts at 800 mA). Size 9 ins. X 9 ins. x 7 ins., £71151-. Carriage Paid. Many other items. S.A.E. List.-Box 283.

Z1FF DAVIS LIMITED, publishers of Radio News, require a first-class man, preferably an active

transmitting "Ham," to edit and prepare for publication MSS. on practical and constructional radio. A sound and up-to-date knowledge of all branches of radio is essential, together with experience in radio journalism or publishing. The position is permanent and offers considerable scope and advancement. Write giving particulars of age, experience and salary require to Ziff Davis, Ltd., Grampian Building, Western Gate, London, W.6.

BARTON'S. CR Tube units containing 21 valves,

VCR 97 tube, 100 kc crystal and hosts of components, £6/10/-, carr. and packing £1. Various other units with VCR 97 tube, 6A, B, etc., from £3/15/-, plus carr. Also various 3 -inch units. 50 and 65 watt modulators, BC -348's, 342's, and 312's from £16. KAAR 10 valve HF receiver, suitable for television, £8. T.G.10 Keyers, amplifiers, valves, etc., send stamp for new list.-Barton, 41 Bedminster Down Road, Bristol, 3.

HRO and 7 coils, bandspread 5 bands, £32/10/-. 2000v wkg., 4 mF condensers, 10/-. 4+2 mF

12/6. 1000v wkg., 10 mF 8/6. All in sealed cartons, plus 1/- carriage. Assorted mica, silver mica and ceramic 2 to 6000 pF, per dozen, 4/-, tubular wire - ended metal, 7/6 ; cardboard, 5/6. Moving -coil mike/ headphone assemblies, 12/6. Two RCA 803's, £2 each. Ceramic Octal Valveholders, 2/- each,-Hindle & Sharratt (G8JA, G4CJ), 103 Redlam, Blackburn, Lancashire. Phone 49320.

RECORDER, brand new, latest model, with matching transformer ; B.S.R. 30 -watt

amplifier, and selection of blanks, cutters, etc. Cost £140. Offers. S.A.E. for details.-Box 309.

MAGNETOPHONE studio -type tape recorder, German manufacture, new condition, precision -

made instrument suitable for recording or broadcasting studio work, etc. Details on request, offers Box 310.

G2AKSee page 280 for Special Offer in Com- munication Receivers. A pageful of

Bargains. COSSOR 339 Double Beam Oscilloscope, unused,

£35. Weston precision portable AC Voltmeter, 0-150, 25-2400 c., £3/10/-. Ex -Govt. VHF Signal Generators, 18/6, carr. paid.-Wardley, 887 Manchester Road, Castleton, Rochdale.

T S and LOGS by MeINERVA. Always new Land attractive designs. Samples from

Minerva Press, Elm Park, Essex. ELECTROSTATIC Voltmeters: Ferranti 0-2000

volts reads DC or AC. 3* -in, diameter flush fitting. Brand new, boxed 21/- each or 2 for 37/6. Post paid. -Storer, Oak Lodge, Wanlip Road, Syston, Leicester. A LUMINIUM chassis to your requirements, any

size, plain or punched, from 3/9.-EAD, 13 Bence Lane, Darton, Barnsley.

4000 -ohm headphones, 8/6 pair. 8 in. 3 -ohm PM speakers, 18/6. 24 -in. PM

midget Celestion, 15/7. 5 -in. Alnico PM, 15/8. All less trans. 6C4 VHF B7G triodes, 10/-. TU8B, 6.2 to 77 me tuning units, 26/6. Selenium rectifiers, 250v 40 mA, 2/6. Solon 60 -watt 200-220-v chisel bit soldering irons, with cable, 15/9. All post free. From National Radio Supplies, 66 Holdenhurst Road, Bournemouth.

USA

VOLUME VI SHORT WAVE MAGAZINE

SMALL ADVERTISEMENTS TRADE-continued.

Gr1®o66D6506C6, 954, 6F7955,

956 KTW6110/6 6K7,c 5/- each.

6SG7, 6SH7, 6SA7, 6SK7, 12SG7, 12SH7, 12A6, 12SQ7, 12C8, 12SK7, CV18 (RK34), NR43 (PM24A), 6/6 each. 6J5, 6H6, 4/ each. Bliley or R.C.A. 100 kc xtals, 17/6 each. -A. C. Houle, Loose Village, Maidstone. Phone 83579.

TX Power Packs, 200-250v, 50 c. input, 1200v 200mA DC, smoothed output, metal rectifiers, relays, etc.,

H.D. job in ventilated Metal Case. Rx Power Pack 200-250v, 50 c input, 6.3v at 13 amps. DC and 250v 110 mA smoothed output, metal rect., H.D. in ventilated metal case. Both brand new, originally cost over £60. Real bargains at £16 pair, with carr.-HUGHES (LOWESTOFT), LTD., 88 TONNING STREET, LOWESTOFT, SUFFOLK.

YOUR Xtals. Ground to your frequency or re- activated. Send S.A.E. for details and list.-D.

Shackleton, 167 Margaret Street, Ashton-under-Lyne, Lancs. D EWINDS AND SPECIALS. MAINS, INTER -

VALVE, OUTPUT AND MODULATION TRANSFORMERS MANUFACTURED TO YOUR SPECIFICATION. COMPACT TRANSFORMER FOR BC -348, 26V FILS., NO ALTERATION TO WIRING, 36/- ; CHOKE TO MATCH, 10/6. 2.5 mH 120 mA RF CHOKES, 1/6. TRADE ENQUIRIES INVITED.-G6VS, CARLTON COILWINDING CO., 8 CHURCH ROAD, BIRKENHEAD.

WHY buy IF's? Wind your own on a KAYNITE w'nder. Stamp brings particulars from manu-

facturers.-Richard Sheargold & Co., Sunbury -on - Thames.

BFO UNITS, complete in screened box, less valve, 5/6. Power packs for Receiver 1294 15/-,

postage 2/-. 7R7, 7Q7 Valves, surplus to requirements, all new. R.T.S. Res and Cap. Bridge, Model EA.20, £10. B.P.L. Signal Generator, Model R.S.600, £12. AVO Valve Tester, complete, - £12.-Radio Repairs Unlimited, 381A Dunstable Road, Luton, Beds.

VALVES, new and unused, ex -Govt., at 8/9 each: 6K7, 6K8, 6V6, 6F6, 637, 6Q7, 6L6, 5U4, 5Z4,

MU14, EL32, EF50. S.A.E.'for list. C.W.O. only.- A.G. Supplies, 90 Melrose Avenue, Mitcham, Surrey.

G 5 C P offers American multi -ratio 200 watt modulation trans. 25/-, ratios supplied. Oil

filled 4 MFD 1000 volt working 3/-. 1 MFD 1500 volt 2/6. 35 K. 35 or 50 W. vitreous bleeder res. 1/6. Black. crackle steel cabinet and chassis 20 in x 5 in x 8 in, 6/6. BC348's R.1155 and Scope, S.A.E. for details :-33 Manley Road, Sale, Manchester.

READERS' ADVERTISEMENTS 3d. per word, min. charge 5/-, payable with

order. Box numbers 1/6 extra.

GOING ABROAD : For Sale. Communication Receiver 1.7-7.5 mc, 9 valves. Specially made

cabinet, Brand new £30. 12 in. Vitavox Spkr., Brand new £5. Various components, valves, etc. - 212 Woolwich Road, Charlton, S.E.7.

BC -312D, Mod. for Mains, Crystal Phasing. Good condition. £14. 10. 0. or offer.-Capell, 115

Wood End Gardens, Northolt Park. WANTED. Portable DC/AC communications re-

ceiver such as Hallicrafter S-39.-Martin, Three - ways, Crown Street, Dedham, Near Colchester, Essex.

TRANSFORMERS. 500-0-500 volts 250 mA, 5v 4a, 22Ibs. 25/-, carriage 3/6 ; 385 volts 50 mA 4.1v la,

4.25v 2-3a, 35/-, carriage 3/6 ; 860-0-860 volts 50 mA, 5v 3á, 22/6.-Box 280.

SALE. Termans Radio Engineers' Handbook, £1. 830B, with socket, £1. 832, with socket, £1. Or

exchange for good bug key.-G3CSP, 89 Tideswell Road, Sheffield 5.

TANNOY 60 -watt amplifier, 4 KT66, 4 635, 2 418, 230v. 50c., £10. No valves. Buyer collects.-

Brown, 62 Bower Street, Maidstone.

283

ANNAL SENIOR HRC'

Nationals, RCA AR88, AR77, RME 69,99, Howard, Hallicrafters, Coll- ins, etc.-always something new in high-grade com - munications receivers. Your present equipment accepted in part -exchange.

All mail enquiries given prompt attention. Staff Calls: G3AFH-G3BVD-G3AJU-G3DDO.

* SHORT-WAVE LISTENERS, AMATEURS, ENTHUSIASTS !

2}d. stamp brings our Special Monthly Bulletin. A host of up- to-date lines at keen prices.

Specialist Agents for Eddystone Short Wave productions. Large stocks 504, 640 (now £39/10/- Tax free) Components, Accessories, inc. new 640 "S" meter, the new Modulation indicator unit-immediate delivery all lines from stock. Home Export and Trade inquiries receive immediate attention. Telegraphic Address: "Jonrad" Macclesfield.

iOHN5ONs (RADIO SPECIALISTS)

MACCLESFIELD. CHES. TEL. 4080

ids f A HEADQUARTE SAY G2BAR FOR RADIO EQUIPMENT AND COMPONENTS LOW FREQUENCY CHOKES Max. D.C. Inductance Resistance Weight Price

100 mA 10 H 100 ohms 2# ib 7/6 100 mA 20 H 350 ohms 4; lb 10/6 250 mA 10-15 H 100 ohms 6} lb 10/6 250 mA 15-20 H 200 ohms 6; lb 10/6 500 mA 15-20 H 80 ohms

Please add Postage. 20 lb 25/0

VIBRATOR UNITS 12v input. Output 120/150v. 50/30 mA, including GB and LT for battery valves. U.S. made by Jefferson - Travis to A.M. specification. 19/6 each, plus postage. CHANGE -OVER RELAYS 6 -pole 2 -way, as used in 1154 Transmitter. Operates from 3/6v, can be used for switching complete transmitter and receiver, including aerials. Price including postage 7/6 each. IN22 SYLVANIA CRYSTAL DIODES Designed for general instrument use, such as Test Probes, Power Indicators. Ideal for field strength Meters, Monitors, etc., using up to 5 mA movements. 2/6 each. 10 for LI post free. METERS 2 in. Flush Type, 0-120 microamps. F.S.D. Calibrated 0-120. Used as Oil Temp. Meters. Ideal for use with Crystals above for field strength meters, etc. 3/- each post free. Write to us for all your equipment and components. We offer you keen service and prices.

Your Order and Enquiry dealt with same day.

ARTHUR H. RADFORD A.M.I.E.E. (G6YA) A.M.(BRIT.) I.R.E.

28 Bedminster Parade, Bristol, 3 Telephone : 64314

284 SHORT WAVE MA GAZINE JUNE 1948

IFor FIELD and SHACK Use

*NEW POWER PACK* giving 170v at 80 mA and operated from

110/250v 50 c.p.s. A.C. Mains

or a six -volt car battery

Fully smoothed. Size : 102" x 6" x 4f". Black crackle case, complete with 6X5

valve, Leads and Plugs

f5/ 19/6 net cash

Carriage Paid

Write for full specification or send your

order, with cash to:

G2YO Rainbow Radio Mfrg. Co. Ltd.

Blackburn, Lancashire

G2OO SPECIAL offer this month. Combined 12v Vibropack and LF amplifier unit No. I, output 120v 30mA. The LF amplifier is complete and uses a twin pentode ATP4. Two centre -tapped selenium rectifiers and many other useful components, guaranteed perfect as new, only 24/6, post 1/6.

EXTRA -special offer for the V.H.F. enthusiast, a few only.

Radio Altimeter Units R.T. 34 APS 13, transmitter and receiver working on about 430 mc, containing 16 button -base tubes, one VRI05/30, five 6J6's, two 2D21,'s and nine 6AG5's complete with all tubes as new, fI0/15/-, delivered to your door for less than the cost of the tubes at surplus prices.

POWER SUPPLY Units No. 4 Mk. 1"about 300v. 100 mA, output containing four metal rectifiers (worth 7/6 each) 500v wkn. Electrolytics, 12v Vibrator, Transformer, Panel light and many other items, a gift at 19/6.

For this months valves see Classified advertisements.

A. C. HOILE LOOSE VILLAGE, MAIDSTONE, KENT

S MALL ADVERTISEMENTS READERS'-continued.

B C342Han new, 230v, MCR1 complete, new, 10 -watt 'Phone/CW Tx, with mods.,

coils, 160, 80, 40. What offers.-3AHK, 153 Old Castle Road, Llanelly, Glam.

COMPLETE set "Mains Power Pack" for driving Marconi 1154. Tran's and Receiver as used on

ground stations, £12. set. -Bishop, Manuden, Bishops Stortford, Phone Stansted 3315.

BC348Lplus separate power pack (AC), fine

condition, with diagrams. First offer over £22. secures.- BRS-14,483, 28 Allenby Road, Cadishead, Manchester.

BC348Communication receiver, perfect condition, with motor. Filaments wired for

six volts, ready for power pack, £18.-Scales, 12 Tuthill, Scarborough.

FOR sale R.107, good condition, Bargain, £12. Wanted 7-14 mc Bandspread HRO coil.-Brigham,

45a Northumberland Road, Tweedmouth, Berwick. FOR sale. Hallicrafter SX-28 Super-Skyrider. Also P Hallicrafter S-20 Sky Champion. Both excellent

condition. What offers ?-Box 281. COMPLETE B2 Trans/Recvr, with power supplies

and accessories, £12. Modified 1116A Battery Rx 142 kc-20 mc in 7 bands, £6. Ham -built CRO, Ampl or Attenuators, etc., £10. 520 kc-1500 kc, 12v. 6 -valve Superhet, variable coupling IF, £6. 7BL Trans/Recur tuneable 112 mc, 15 valves, £6.-42 Southfarm Road, Worthing.

35DDYSTONE, SERVICE NO. B34. £1 8XOFFERED OR CIRCUIT OR BOOK. REPLIES PLEASE. -16 CONISTON ROAD, RED- DISH, STOCKPORT.

COMMUNICATIONS Receiver, RF, 2 IF, BFO, Filter, 2 watts output, 6 ranges, 1.5-23 mc continu-

ous, £20 ; or complete B2 and £10. Going portable. -G3AGQ, Cheznous, Beggars Bush Hill, Benson, Oxon.

1 AA WATT Tx , CW, TT Modulation, TT, Carrier,

8v Rx, Power Supply, £15.-14 Oswald Terrace, Leeds 12.

COMPLETE Portable Station, in cabinet, circuit supplied, 3.5-14 mc. Rx superhet, 4 Mullard E

valves, loudspeaker, Tx, 6L6, commercial make. 6v. DC supply, vibrator, easy conversion, £13. plus carriage.-Box 282.

Chassis, 1191A Wavemeter 1625, 807, VT100, 1235 RKR72, VT.93, 1629 Tubes

unused. Offers all or part to :-Franks, 11/13 Green Lane, Leeds 12, Phone Leeds 22218.

R1155

AR88LF S -METER, Eight Spare Valves, £50 or offer. New Crystal Microphone, £2.

-Willmott, 20 Rutland Gardens, Dagenham, Essex. RAND new Philco 43 Transmitter, using two 813's in the final. 'Phone, CW, MCW, VFO, complete

with 19 valves, inst. book. Exchange above for HRO Rx. Vibroplex bug key 30/-.-14 Styal Road, Gatley, Cheshire. Phone GAT. 4367. `,WANTED. GPO double -current Morse Key, VI' Glass or. Brass cover. New or second hand.

Good price paid.-Box 284. BRAND New B2 Transmitter-receiver complete

£12. 10. 0. B2 receiver and pack for 230v AC £6. New US xtals : 7140, 7173.3, 7206-67, 7240, 7273.3, 7306-67, 7340, 7373 B, 7406.67, 7440, 7473.3, 12s. 6d. Valves, Boxed, 805 £2 ; EBF11, EF11, EL11, 10s. ;

VR65's, EF50 unboxed 3/6 ; CV57 15s. ; GTIC, 7A8, 7C7, 12SG7, 6AG7, 7117, 7/6. Cyldon Tx condenser, 250 pF max. 0-15 in. spacing, ceramic insulation, polished vanes, heavy construction, £2. 10. 0. New Gardners Transformer, 500-0-500 250 mA, 2 x 6.3 3a, 5v. 3 '5a.-A. Skillman, 74 Franchise Street, Weymouth, Dorset.

FOR sale 3-5 to 58 mc, 150 -watt 'Phone/CW Trans- mitter, PP35T's, Rack Built, All stages metered,

Xtal Mike, VFO Unit, AR88 Receiver, frequency meter, Best offer whole or part. S.A.E. full particulars. -Box 285.

VOLUME VI

SMALL ADVERTISEMENTS READERS'-continued.

SHORT WAVE MAGAZINE

LTNIQUE bargain. Midget Tx made for US Agents. About 6 watts on 80, 40, 20 m., measures only 3 x

10x2 in. with a Power Pack for 6 -volt, 110v. or 220/ 230v. which will also charge a 6v. Accumulator from 110v. or 220/230v. Absolutely complete with valves, key, etc., £10. Rx same size works from same power pack, 3-18 mc, £1. extra.-Ingram, 46 Upper Richmond Road, S.W.14. SELLING UP : Eddystone 358x, coils 90kc-31mc,

£22 ; Harvey UHX10, power pack, coils 1.7-60 mc, xtls 1.7, 3.5, 7 mc, mike, key, £30 ; R1481, £7 ; T1154, £7 ; MCR1, power pack, coils, 'phones, £7 ; TR1196, £5 ; TR1366, £5 ; Simpson turntable, £3 ; or £80 akes all.-Box 288. SALE-Transmitter T.1115, VFO or CO -FD (PX25)- 7 PA (TZO5/20), Built-in Modulator, 160-80-40-20,

'Phone or CW, complete with set of coils, etc., £10. Or part exchange for BC342 or 348.-Box 287.

C R 100professionally overhauled, new mains

transformer and electrolytics, in perfect order. £25 (buyer collects or carriage extra). MCR brand new, but less battery, £5. Hunts C.L.R. capacity/ resistance bridge, as new, £9. Weston E.665 Selective Analyzer, £12. Valves in perfect emission, ML4, SP41, 77, 6S6G, 6H6, 12A6, 7/6 each. G4RS, 17 Tudor Avenue, Bebington (Telephone Bromborough 1012).

COMPLETE commercially -built transmitting - receiving station, 200/250 volts AC or 12 volts DC,

15 -watt Tx covers three amateur bands. VFO/Crystal, CW, MCW, 'Phone. 5 -valve superhet receiver, plus MW broadcast band. Ideal QRP rig. £30.-Box 289.

OFFERS, cash or barter invited for new crated Canadian Philco C.43 Transmitter. Size 4 ft. x

2 ft. X 2 ft., metered, semi -valved, VFO, Exciter, PA Aerial Coupling, Modulator. Uses 807's, 813's. Present coverage 2-12 mc. Too large for present QTH. Must dispose.-Box 286.

FOR Sale-RME DB -20 Preselector, all bands to 28 me ; self powered ; good condition and working

order. Offers to : G6KJ, 20 Church Street, Buckingham.

AVO All -Wave Oscillator, hardly used, £9. New valves (2) 6C8, (1) 6J8G, 10/- each. (2) VP23, (2)

HR210, 5/- each.-Box 291.

TROPHY 6-just re -aligned and overhauled for 65/- -best offer over £10/10/-, or exchanges.-G6BB

35 Criffel Avenue, London, S.W.2.

AR88D for sale. Excellent condition, with handbook, £45. Would consider exchange

with cash adjustment for S27.-G3DCV, 75 Elwyn Road, March, Cambs.

WANTED.-Holder (11 -pin) for 2AP1A CRT, with screen preferred. Assembly with tube considered.

-Symons, 9 Nicholas Lane, Bristol, 5.

TAYLOR Model 45 Valve Tester, £11/l0/-. Ferranti Woodascope Test Set with 4+ -in. CRT, requires

little attention, £4. Worth double for componenets. Woden 750-0-750, 150 mA, £2/7/6. Other components S.A.E. G3PO, 54 Granshaw Close, Birmingham, 30.

WANTED : B2 pack Mk. III, 12A7 valve, medium and 20 -metre coils for MCR1, 145 VFO and pack,

75 -watt modulator, IN34 xtal. Will sell BC -348, new, £16. Or exchange 1155, cream cellulose sprayed, chromium plating. S.A.E. list gear for exchange.- Box 290.

A R88D5. RCA BC -348, noise limiter, S - meter, built in 28 mc converter, £24.

1155 modified, £11. All re -aligned and in good condition. Buyer collects.-G8HH, 65 Chart Lane, Reigate, Surrey. Tel. 3968.

MARCONI CR100/8 MOD. Has A.N.L., 600 -ohm line output, etc. Offers over £30. R103a, new

valves, 230v AC or 6v DC, complete with manual, £10. Zenith transformer 600-0-600v 60 mA, £1. Ditto, 4-0-4v, 2 amps, 15/-. MCR1 complete, coils, power pack, spare battery, 'phones, £71101-. Wanted B2 Tx/Rx, power pack, coils, complete.-Box 294.

285

BARNES RAD-ELEC CO 2 Elmdale Road, Penn, Wolverhampton

Calling all RI 16 owners, all constructors and transmitters. WE can now supply the special aerial socket plug and 2 -pin screened D.F. plug for R1116 at 119. post free the pair. For the complete "air tested" receivers see S.W. Map. page 214 last month. They will all be gone before winter season, don't be disappointed by delaying. NEW June catalogue, hundreds of bargains. Those on our mailing list will have priority and often advance notice. FINE powerful 2 -pole ring magnets 4" dia 1+" wide 2/6; 2" wide 3/-. Crystal Monitors in cabinet (3 -valve chassis) dozens of parts £1. Valves-V.5. 110A (S.130) neon stabilisers 15/- pair for 230v. Plugs-At last ; Jones female plugs with screened cables 10 - pin 4/6; 12 -pin 5/6. Batteries - 30,000 for portable sets, surplus bargain, 1.5v, 2/- for four. Variable Condensers 1500v 50 P.F. for Tx, robust, cheap at 5/6. Fitted boxes of fine transmitting coils; fixed and variable, 11 for 25/-. Special offer of 4 mfd 350v condensers If" x If" x 3", 2/-. New control panels with 2 mc meters, switches, etc., £1 each to clear. STOP PRESS :-We have just bought whole of the stock of well-known B'ham firm and lists are in preparation; for a start we offer (to clear quickly) alum. boxes containing: cross over switch; 3 position switch; 2 knobs; } meg vol. control, insulated- aerial terminal, 1000 ohm resistor, scale plate, earth terminal and a free bench tray with each at 3/- only.

1154 Tx. as illustrated, complete with valves, for phone, C.W. or M.C.W., 2/PT15's in the P.A. Price including carriage, £8.

BC603 Rx. Frequency Modulation receiver, with 10 valves, £7 10s. carriage free. Type 10 Remote Control units, 25 Watt rack mounted amplifiers, mains power pack, brand new, a bargain at £15 10s., carriage free. High resistance headphones, 8/6., 2 mfd. 500 VW condensers, 9d., 25 mfd 1500 VW, 1/-, EF50's, 5/-, and dozen of other items in our catalogue, which will be sent post free on request.

TORBAY ELECTRIC 43 COLLEY END PARK, PAIGNTON, S. DEVON


"You'll probably get it at . . . .

SMITH'S of Edgware Road" The fact that this remark is often heard today is the result of twenty years of specialising in WIRELESS COMPONENTS. We know your needs and do our best to meet them (taking advantage of disposal stocks to keep costs as low as possible). You won't see many sets here, but you WILL see an amazing variety of components, materials, valves, speakers, test gear, cabinets, technical literatureb etc.

H. L. SMITH & CO. LTD 287-9 Edgware Road, London, W.2

Near Edgware Road Met. & Bakerloo. 'Phone PAD 5891. Hours 9-6 (Thurs. 1 o'clock)

high values Bandspread Short Wave Converter.

Worthwhile Short Wave Listening on your Radio. Hundreds of thrilling s/w stations from all over the world. Long-distance Signals. ,Ease of Tuning. Logging Scale. Two Models available. Ask for Literature.

1

D ULLS(d,) 246 HIGH STREET, HARLESDEN, W.W.I() £9-9-

H.P. Radio Services Ltd., offer

TUNING UNITS TU 8-B 6200-7700 Kcs. TYPICAL UNIT TU 6-B 3000-4500 Kcs.

1. (2) Vernier precision dials. 2. (1) Variable capacitor 20-135 mmf. 3. (1) Variable capacitor 20-156 mmf. 4. (1) Variable capacitor 8-26 mmf. neutralising. 5. (1) 00003-2000V capacitor CD -mica. 6. (3) 00009-3000V capacitor CD -mica. 7. (2) 0004-5000V capacitor CD -mica. 8. (3) 0001-3000V capacitor CD -mica. 9. (2) 4 position ceramic band switches.

10. (2) RF chokes. 11. (1) Tank coil ceramic former with tapped antenna

coupling coil 12. (1) Tank coil-ceramic former. 13. (1) Parasitic suppressor. 14. (2) Ceramic flexible couplings. 15. Banana jacks, stand-off insulators. 16. Handsome black cabinet 17k" x 7k"x 8".

Brand New 19/6 (Carr. Paid.) Despatched per pass. train by return

H.P. RADIO SERVICES LTD. Britain's Leading Radio Mail Order House,

55 County Road, Walton, Liverpool, 4. Te1.:Aintree1445 Safe Delivery and Satisfaction Guaranteed.

Specialists in Ham Radio. Staff Call Signs G3DLV G3DGL

SMALL ADVERTISEMENTS READERS'-continued.

WANTED-A BC -453A Beacon Receiver in good condition, or Receivers "ARCS" or "274N"

complete or in parts. Also a Panadaptor 230-250 AC, Type SP44. Offers to G2BYF, 76 Broadway, Sheerness, Kent. 5_1 ()METRE double-superhet, AC 200-250, all coils,

nearest £25 ; H.M.V. electric gramophone unit, almost new, £10.-G3BGS, 149 The Moors, Kidlington, Oxford.

FOR Sale. Sky Champion, £23 ; Weston Analyser E772, £17 ; Ribbon Mike with stand, £51101- :

two Weston 242A Valves at 10/- each. 9001, 9002 and 832 valves. Offers ?-Box 293 .

FOR Sale. National HRO Communication Receiver, as new, with Power Pack. Cost £60, sell for £38.-

J. Burns, Caversham Lock, Reading. HALLICRAFTERS SX-28 Super Skyrider, condition

as new, with Instruction Book, £55 or near offers. Spare set valves, £4. Marconi CR.100, perfect condition, £35. National HRO Coils, 100-200 kc, 0.5- 1 0 mc, 0.9-2 me ; with bandspread 1.7-4.0 mc, 14- 30 mc. Offers.-Box 295.

1 1 55Complete-power pack, 6V6 output, 5 -in. L.S., New Panel, S-Meter-£17 or near offer. New

valves -6L6, 6AK5, 6SN7/6T, 636, EF50, 6AC7, 6SH7, all 10/- each.-A. H. Martin, 30 Mosshead Road. Bearsden, Glasgow. ISALLICRAFTER Skyrider Marine S22R 110 kc to S 118 mc, 9 valves, Gear Drive, good condition, £17. 31 amp. thermo-couple meter, 15/-. Valves as new, boxed-PP3/250, 6116, AC/PEN, MH41, 12Q7GT, ECH3, 1Q5GT, 1H5G, TH4B, AC/VP1, 5/- each. 2 -volt superhet valves, 3/-. Exchange considered.- P. Malvern, 12 Rotunda Terrace, Cheltenham.

H AM Surplus. Brand new. Few of each at 7/6.

42, 6F6G, 6K7G, U14, 6L7G, EF39, ECH35, 5V4G.-G3BBA, Cross Road, Towcester, Northants.

522 100-156 mc Transmitter/Receiver, £18 BC221, £18. R1155, £10. Valves: 813's 50/-,

829, 832, etc., Transformers, Crystals, S.A.E. List. Offers.-Box 296.

HALLICRAFTERS, S2OR, Sky Champion, 6.8-550 metres, good condition, £20 or best offer.-Norman,

45 Collingwood Avenue, London, N.10. ATEW gear :-T55, £6. 803, 60/- (base 10/-). 829B, 1V 60/-. 815, 70/-. HK54, 45/-. 808 30/-. 1852, 10/-. 210, 10/-. Woden de luxe 1250v transformer, £6/10/-. AVO Signal Generator, mains, £10. M/C meters from 10/-. Used but perfect :-T40, 30/-. 800v transformer, 50/-. NC81X, offers. 813's, offers.-R.H. Webb, Bigbury-on-Sea, S. Devon.

KENNY Private Hotel, Bigbury-on-Sea, S. Devon. Vacancies June, early July and September. Hams

especially welcome. Write for brochure. ASSORTED used valves, inc. U50's, etc., 3 for 11/-.

No selection. Philips 6v Receiver (no valves), 50/-. Bluespot AC/DC, 3 bands, 80/-. Lissen AC Receiver, 65/-. R1155, £15.-Box 297. QALE. R1116A Rx, Perfect, 142 kc-20 mc, original

transit case, circuit, eliminator, trickle -charger, £10. Avo Minor Universal £5.-G3CZW, 4 Brighton Road, Newhaven, Sussex.

RA155fully modified, with built-in 100 kc xtal calibration, £12. CO -PA, (807) with built-in

500v 200 mA PP, external fils. 6.3 and 4v, also stabilized HT output for VFO, metered, £8. Valves : 955, 954, 807, 10/-. EF39, 50, EB34, RL16, 17, etc., 5/-. R1155 and B2 Spares, etc. :-G3JA, 8 Thurlstone Road, Luton, Beds.

PROCEEDINGS Brit.I.R.E., Jan. 1946 to Dec. 1947. 2 Vols., unmarked, £2. Midas F2.5, Taylor, Hobson

lens, 9.5 nun Cine-Camera/Projector, as new, £7/10/-. Micro -switches, 2/6 ea. CR100 : 6AK5 1st RF, Xtal, Audio Filter, 60 kc to 20 mc, Noise Limiter, S -Meter Bridge, 12 valves, perfect, £45. Flexible steel mast guy wire, 3d. yd. Dural Tube and Sheet, state requirements. Letter with S.A.E. to Radio, c/o 40 Brathway Road, S.W.I8.

SCR


'S announcements now appear in the Trade Small Advertisements column and on

Page 284.

HRO COILS. Ex. Condition, 14 0-30 mc BS, (3). 14-0-30 mc GC, 9-2 05 mc GC 48-96 mc

GC, 50-100 kc, 100-200 kc, 180-430 kc, £3. each.- Box 298.

/6. CR1001000 kcCoil kCry Crystals, 10/6.T15 Numerol.s 9Rx

Valves, Meters, etc. S.A.E. for List. -Box 304. METRE converters, RF Units Type 27 (65-85 mc)

and Type 31 (56-72 mc), 27/6 each. RCA 801's, 15/ - each. -J. Short, 112 Southwick Street, Southwick, Sussex.

WANTED, Halfleafters SX28, AR88, or HRO Receiver, State Condition and Price.-G3BJB

"Keswick", Saint Andrews Road, Malvern, Worcs. B S D AC Amplifier, 3 stage, 2 PX25 Parallel, 500v.

HT Transformer, 2 Chokes, output transformer. Offers.-G4LC, Russell House, Rye.

ARMY No. 12 Transmitter, 50 watts CW, 25 watts phone. Continuous coverage 17.5 mc. to 1 2 mc.

VFO or Crystal control. Complete with key, mike. etc., ready to go on the air. New condition. £30 B2 Transmitter complete with coils, etc. (less power pack), New condition £3. -Box 303.

1155A

SMALL ADVERTISEMENTS READERS' -continued.

G200

nearly new, built-in power unit, output stage, and midget speaker, Transit case,

£20.-Stebbings, 91 Ridgeway Hill, Newport, Mon.

RAF 1082 Receiver, 1083 Transmitter, 80 watt, 1200 volt Rotary Transformer, Key, Neutrali-

sing unit, etc. Received from M.O.S. Sale. Marked RAF serviceable Spare VT 25. Bought in error, £8. 10. the lot. Carr. Paid.-Gidman, Loddon, Nor folk.

2 R.0 A .AR88D.

540 kc to mc, Matchin Speaker, £45. CR100350 kc to 30 me

£22. 10. Both good condition. Buyer collects or arranges transit of above. BC -312N, Same as BC -342, but 12 -volt operation, £11. Carriage Paid. -Taylor, 75 Edgehill Road, Winton, Bournemouth.

VSSRCommunications Receiver and Matched Speaker, in perfect condition, £28.-39

Veda Road, Ladywell, London, S.E.13.

5/1O 6 Modulator

Complete, Spares, Power Supply, Relay Controlled, 19 in. Rack, £25. Offers. 5 -metre Tx KT61-6F6-807, Xtal, 3 Element Close Spaced Rotary, 16 ft. Mast, £10. 2 x 2 Element stacked beam 5-10 metre, Coaxial Feeder, £5. S.A.E. Details. Phone Haslemere 337. Gammon, 20 West Street, Haslemere.

R 107 9 -valve, 17.5-1.2 me AC, or 12v. battery, good condition, £15. Carriage Paid. Box 302.

SALE. Hallicrafters Receiver S.38 Perfect, New Condition, £20. Brand New Eddystone VHF

Convertor, all coils, spare valves, plus power pack, £11. Crypto Rotary Converter 220-240 DC to 220-240 AC, 330 watts, £7. Webbs bug key 35/- new valves. One 813, 40/-, One 814 35/-, One RK25 12/6, One 802 15/-, Three 1625 10/- each. -S. Abbott (G3JU), 139, Mel- bourne Avenue, Newington, Ramsgate, Kent.

CLEARING surplus gear. Type 55A mains operated AF Oscillators, £3/10/-. Wavemeter W.1270 25-

130 mc dual unit, mains operated, £4. Various Power Packs, 12v. DC -230v. AC Convertor, or exchange, 24v. Ditto. -Martin, Gables, Yoxford, Suffolk.

8325 with ceramic base -20/-; less base, 17/6 J the ideal 25 watt PA up to 200 me ; slightly used, but money back or replacement guarantee. 2 -stage 3 -watt AC amplifier with spare set valves, 50/-. MCR1 with Mains Pack and Miniature Speaker, £8. -Box 301.

POLARIZED Relays, Standard Type, 12/-. Double

Current key with switch, 10/-. Handset, inset, receiver and cord 7/6. Long 'Phone cords 1/6. - Burnley, 37 Cherryalley Gardens, Belfast.

HRO Broadcast Coils, E and G, £2 each. One HRO Tuning Condenser, complete Dial

and Drive, £4. New. -Box 300.

MORSE CODE Training FOR BEGINNERS

AND OPERATORS IRREFUTABLE EVIDENCE of the value of the Candler System of Morse Code training is given in the " extracts from students' letters " included with every copy of the Candler

" BOOK OF FACTS" sent post free on request.

READ THIS LETTER FROM A CANDLER STUDENT ! Dear Sir,

Some time ago you sent me the first five lessons of the Junior Code Com-se. IIni ortunately the extreme pressure of military matters made it impossible for me to give all the time I should to the course.

(I should explain that T have been training newly enlisted Royal Signals personnel.) However, now I have been demobbed, I have started on the course and am very pleased with the progress I am making. I have already got my Amateur Licence.

Could you please send me the remaining five lessons so that I can continue right on with them when I have finished lesson 5? If my progress continues as at present, I shall have got farther than I ever thought possible, but it seems so easy this way.

I close, wishing you all the best for the future, and assuring you that I will recommend your course to anyone who asks my advice on learning Morse.

Yours faithfully, E. N. B.

P.B.-An old hand, whom I met personally after many contacts on the air, said: " It's a treat to hear a decent fist nowadays." Was I pleased I as I had only been working on the course for two menthe.

SEND NOW FOR THE CANDLER "BOOK OF FACTS"

THE CANDLER SYSTEM CO. (55S.W.) 121 Kingsway, London, W.C.2

Candler System Co., Denver, Colorado, U.S.A.

E oAO Co Short -Waive Equipment

Noted for over 15 years for Short -Wave Receivers and Kits of quality

One Valve Kit, Model "C" Price 20/ - Two "E" 43/ - These kits are complete with all components, accessories, and full instructions. Before ordering send stamped addressed envelope for descriptive catalogue. Note new sole address :- "H.A.C." SHORT-WAVE PRODUCTS (Dept. VIC.) 66 New Bond St., London, W.1

E®®YST®NE '504,' '640,' '680,' and

Full range of S.W. components Also

Valves, condensers, transformers, resistances, etc.

All C.O.D. orders promptly executed. 52 -page catalogue If. post free.

B.T.S. THE Radio Firm of the South.

63, London Road, Brighton I, Sussex. Phone: Brighton 1555.


TU5B You can make a Super V.F.O from the. Instructions which the A.R.R.L. League has given permission to reprint from Q.S.T. with the U.S. Signal Corps TUSB Tuning Unit. Price complete with

instructions

U S 22/6 /`W

B2GESR? HARLESDEN, N.W.10 -I- 3/6 carriage

WE OFFER A large range of used and new Test Equipment, Converters, Recorders, Amplifiers, Motors, Transformers, etc. All guaranteed and at very attractive

prices.

We buy good modern used equipment of all types for spot cash.

UNIVERSITY RADIO LTD. 22 LISLE STREET, LONDON, W.C.2.

Tel.: GER 4447 and GER 8582.

MAINS/BATTERY

MOTOR Fitted reduction gearbox. Suitable for driving medium -size models. Runs off 6 or I2v. batteries or 200-250v. mains (A.C. or D.C.) ; overall ,

measurements 8" x 4" x 4" Post free Ju - ELECTRICAL EXPERIMENTERS ASSORT- MENT. More than 100 parts, including Resistors Switches, Relays, Plugs, Contactors, !/ Terminals, etc. Post free DINGHY MASTS (ex-R.A.F.). Telescopic Alu- minium, 15" long, opens to 9'. Very strong.

®/6 Ideal fishing rod, flag mast, etc. Post free v MERRIBULL PRODUCTS

66 Cromwell House, Wood End, Green Rd. Hayes, Middlesex

COULPHONE RADIO "The Return -of -Post Mail Order Service" 88 DERBY STREET, ORMSKIRK, LANCS. A personal service for the amateur constructor and experimenter. Pexolln Strip, 2" wide,2d inch. Eddystone S.W. Equipment. Delivery 640 ex - stock at 639/10/0. S.W. Manuals, Nos. 5 and 6, 2/8 post paid. Over 5,000 -valves in stock. British and American. All WEYMOUTH Products. Bright Aluminium Chassis, 16 S.W.G., 4 sides, 3" deep, 10"x6", 10"x8", 8/6; 12"x9", 10/6; 14"x 9", 16"x 8", 11/6 ; 20"x 8", 12/6. Ferranti 25 -watt Modulation Transformers for push-pull 807's to 807 P.A., 25/-. Ferranti Electrostatic Voltmeters, 3", 0/2,000, 28/-. New Goods Only. C.W.O. or C.O.D.

Send 2d. Stamp for current 24 -page catalogue

SMALL ADVERTISEMENTS READERS'-continued

VALVES 6C4, 7N7, 7A8, 6AC7, 6AB7, 10/-. 6S117, 6SN7, 2X2, 6SJ7GT, 6SK7GT, 7/6. Electro Voice

600C Dynamic Mic., £2. Vibraplex, £21101-. Postage -Box 299.

R 11 SSFín nice condition, £11/10/-t for quick sale.-Leger, 18 Little Heath, S.E.18.

WANTED SCR -522 Transmitter/Receiver.-A.J. Cryer (G2BXL), 33 Prince's Way, Fleetwood,

Lancs. CONVERTER, working order 40-65 mc (Receiver

10-60 mc AC 250v.). Full details-S. Brown, 6 Addison Villas, New Eastwood, Notts.

SALE. APQ9 420 mc Radar Tx, uses PP 8012 L.L. oscillator, also 2-807 and 3-6AC7, £31101-. 2.5

KVA Autotrans., 230-115 volts, £2. RCA 500 watt Mod. Trans., £2/10/-.-Kimber, 7 Van Mildert Terrace, Stock -on -Tees.

CR11 0OCommunications Receiver. 60 kc-30 mc. All grey, with matched speaker, ANL,

S -meter, spare set valves,,instruction manual. Excel- lent condition, £40.-Daish, 302 Bitterne Road, Southampton.

AR88 For Sale. Perfect order, cabinet model £55. R.C.A. ASB8 12 -valve 460-500 mc Receiver,

Lighthouse RF stage, Unused, £71101-. B2 Tx/RE. Power Pack, Xtal, 'phones, key, etc., in two steel cases Brand new £101-/-. Collins Tx 25 -watt 'phone 50 watt CW, 1.5 to 12 mc, Xtal or VFO. Separate 12 -volt power pack, £20. HRO Junior, 5 Coils, S -Meter, etc. £32/10/-. 4 new boxed 636, 15/- each. 815, new, £2. Letters only :-292 Kingstanding Road, Erdington, Birmingham 22a. ,

FEW new 9001, 9002, 9003, 8/- : 6AG5, 6C4, 9/-: 6AK5, 636, 101- ; One unused 31 in. PM Goodmans,

Wharfedale, 22/6 ; 5 in. Elac, 4 in. Goodmans, 17/-. Wanted moving -coil PU, recording wire/tape, 6AQ5, SOBS.-Box 306.

DEMOBBED Radio Officer, resuming technical training October, offers services Amateur Radio,

technical or business side, June -Sept. 4 years' overseas experience communications, 15 years radio and television experimenter. Possible permanency or partner- ship considered later -Box 307.

Four gang, straight line frequency condenser, with dial, £5, or nearest offer.

Marconi Model 212 Short Wave Converter. 3-23 mc, in 3 ranges ; complete with metal valve and instructions £4. MCR1 100-1600 kc, 2.5-15 mc, complete with AC/DC Power Pack, 'Phones, Coils, Aerial, circuit, £7 4 Miniature 465 kc IF transformers, 7/6 each. Valves :

7/6 each : 1D8, 3A8GT, IR5, IS4, 4IMTL, TDD4, VP4, 25Z4G, 25L6, 12B8 (2). Mallory 6 -volt vibrator, Type 650. G.E.C. Dynomotor, 28 volts input, 250v 60mA output, 7/6.-Box 305.

BC348RTip-top condition, almost new and

spot-on calibration, xtal filter, etc., for 230v. 50 c.p.s. mains-£25 (internal power supply.) Brand new, unused 813 RCA, two at £3 each. Other items for disposal, S.A.E. for list to-G3BHD, 136 Lincoln Road, Peterborough. 1lTATIONAL FB7A Receiver for sale. Bandspread .1- 1, coils 10, 20, 40, 80, and two other sets general coverage, 6.3 volt valves, £12 ; Power Supply if wanted £3. 750-0-750 volt 250 mA transformer, totally enclosed, £3. 2.8 10 amp transformer 16/- ; also 2.5 volt 2 amp, and 7.5 volt 3 amp, 16/-. AV() Test Bridge, New, £8.-W. B. Stirling, 137 Glasgow St. Ardrossan, Ayrshire.

FOR SALE. Hallicrafter SX28, As New, £50.- H. Welsh, 382 Brockley Road, S.E.4.

5 QMK. 1. complete with two pairs' phones and mikes, °telescopic and sectional aerials in case, all cables

and accessories but no battery. Perfect condition. £8 or nearest offer.-G3BAA/A, 71 Lichfield Road, Stafford. A Q T Q 420 mc/s, 12 valve double superhet £7.

ARC5/BC950 144 me/s Tx, 815, 2-832's, modulation transformer, etc., £9. ARC5/BC942 144 me/s Rx 10 valve, 9 gang tuning £4. Box No. 308.

HRO

VOLUME VI SHORT WAVE MAGAZINE iü

MINISTRY OF SUPPLY SALES are now coming to an end ..... BUT

SALEsgo on for EVER!

A further selection of our bargains is presented-NOTE every item detailed this month is brand new and unused I

LOOK ! A HAND MICROPHONE FOR 3/6. Super quality carbon mike with lead and jack plug. Switch in handle. (Postage 9d.) U.S.A. DYNAMOTORS. Input 28v DC. Output 300v 260 mA ; 150v 10 mA ; 14v 5 amps.

Ideal for DC Battery Chargers. Voltage regulated and fully smoothed. Complete ONLY 15/-. (Carriage and packing 5/-.) OUTPUT TESTER CHASSIS. Complete with telescopic stainless steel aerial. A 6 -valve chassis full of high-grade precision short-wave gear. 22-85 mcs. ONLY 5/-. (Carriage and

packing 2/-.) MCRI POWER PACKS. A Universal power supply to operate on any mains voltage. Designed for miniature receiver MCRI, but suitable for any small superhet. Size 2*" x 3,4-"N 8z". Only 29/6. (Carriage and packing 1/6.)

* SPECIAL ! * THE NATIONAL 1-10a. The new improved version of the popular I-10 super regenerative receiver. Frequency coverage 1 -II metres. Supplied complete with power supply, valves and

speaker. Valve line up :

954, 955, 6J5, 6V6. In- struction book included. £45.

THE MOST REVOLUTIONARY SALES

PRESENTATION IDEA YET EVOLVED BY

ANY BUSINESS HOUSE

THE M.O.S. NEWSLETTER

(Copyright)

Send 6d. for the current issue of this

monthly informative and novel cata-

logue. The extension of our interests

to other types of merchandise will make

this good reading for all the family.

ENGINE -DRIVEN GENERATORS. (DC Dynamos). with shaft. Only 35/-. (Carriage and packing 7/6.) I.F. TRANSFORMERS HIGH "Q". 465 kcs, Permeability Tuned I.F.'s, 8/II per pair; 6 mcs Permeability Tuned I.F.'s, 3/9 each, 7!- pair. A.S.V. INDICATOR UNITS TYPE 6. Latest model complete with 6" Electrostatic CRT, 4 EF50 and 3 EB34 (time base). In transit case with original seals, £3/12/6. (Carriage and packing 7/6.) MODULATOR UNIT TYPE 189. Complete with 2 EF50 and I EA50 valves. Very compact unit in grey steel case. Only 19/11. (Carriage and packing 2/-.) TECHNICAL DATA. RI I I6 2/3 ; Class D Wavemeter 5/- ; BC348 2/3 ; BC22I 2/3 ;

Walkie-Talkie 58 set 3/6; Walkie-Talkie Vibratorpack 6d; R1224a 9d.

24v

* SPECIAL!* Set of valves for

miniature superhet

comprising one each

IR5, IS5, IT4 and 3S4.

Guaranteed new and

perfect. The set for

27/6 or complete with

valveholders 29/6.

1000 watt output. Fitted

THE BURGOYNE SEVEN -SECOND SOLDER GUN IS NOW ,

AVAILABLE FROM STOCK, £4

KOS MAIL ORDER SUPPLY CO., Dept. SWM, 3 Robert Street, Hampstead Rd., London, N.W.I

CALLERS to 24 New Road, London, E.1

Telephone Stepney Green 2760-3906

THE " Q -MAX" B4/40 TRANSMITTER

A complete 40 watt Four Band Transmitter for Phone or C.W. Four Bands 80-40-20-10 metres at the turn of a single switch. Two Tuning Controls only. 40 watts C.W., 35 watts Phone to KT8C Final. Built-in Modulator and Power Pack.

High efficiency Four Band Tank Coil Turret. All essential circuits metered. Provision for Low Impedance input from a V.F.O. Instant Crystal changing from front of panel.

Transmitter

The whole completely housed in attractive black crackle finished steel cabinet, 19 ins. by 10 ins. by 92 ins.

NOTHING EXTERNAL EXCEPT MICROPHONE AND KEY

PRICE

£75 SPECIAL TELEVISION Absorption Wavemeter .. 33/ -

TRANSFORMERS Ceramic Lead-in .. .. 2/6

350-0-350v 250mA, 6.3v 6A, 4v 8A, 4v 3A, Pick-ups (all types) .. . .

E5 15 6 Signal Lamps (red, green, blue or white) .. 2/6 4Kv 5mA, 4v 2A, 4v 2A, 2v 2A, .. f4 7 6

Filament Transformers (all voltages) .. 2Kv 5mA, 4v I.5A, 2v 1.5A, 4v 2A f3 12 6

.. .. El 15 0 PX4, 6L6 & Push -Pull Output Transformers

IKv 5mA, 4v 2A, 4v 2A CT Microdials 100-I .. I0/-

Goodmans 12" Twin Speaker .. ..f8/8/ -

SPECIAL BC22I TRANSFORMER Metal Cabinets, Chassis and Panels

FOR USE WITH METAL RECTIFIER Aladdin Formers .. .. 10d.

175-0-175v 60mA, 6.3v 2A CT .. .. LI 9 6 - Wearite Midget I.F's .. 10/6

'S' Meter for AR88's .. .. 63/-

B.L. Co -ax Plug and Socket .. 3/- @ -MAX Tank Plugs and Sockets .. .. 9d. per pair

CHASSIS CUTTERS Antiference S.W. Aerial .. 62/6

I" or ," (Key 9d.) . , 9/6 B.L. Aerial Kit .. .. 35/9 If"or I4"or 1f" (Key 1/-) 12/6 Valve Cans and Bases .. .. 1/6

Test Meters, Speakers, Electrolytics, etc.

Q -MAX UNBREAKABLE POLYMAX

Stand-offs .. .. .. f" 6d. I" 9d. If" I/ - Beehives .. ... .. .. If" 2/.

OUR ILLUSTRATED CATALOGUE

IS FULL OF USEFUL INFORMATION

POST FREE 3d.

BERRY'S (SHORTWAVE) LTD 25 HIGH HOLBORN LONDON ' W.C.1 (OPPOSITE CHANCERY LANE). TELEPHONE : HOLBORN 6231

Printed in Great Britain by Lochend Printing Co., Ltd., London, S.W.9 for the Proprietors and Publishers, The Short Wave Magazine, Ltd., 49 Victoria Street, London, S.W.1. The Short Wave Magazine is obtainable abroad through the following : Continental Publishers & Distributors, Ltd. William Dawson & Son, Ltd. ; CANADA- Imperial News Co., of Canada ; AUSTRALIA AND NEW ZEALAND --Gordon & GOtch, Ltd. ; AMERICA-International News Company 131, Varick Street, New York. Registered for transmission to Canada and Newfoundland by

Magazine Post. June, 1948.

Documents

EXCLUSIVELY FOR THE TRANSMITTINGVOLUME VI SHORT WAVE MAGAZINE 219 CELESTION Here are two excellent Celestion Speakers with dimensions which make them ideal for use in small domestic